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Retaining Rings


  • Allows Easy Mounting of Optical Components
  • Compatible with Our Line of Lens Tubes and Mounts
  • Stress-Free and Plastic Versions Available in Our Most Popular Sizes

CMRR

C-Mount (1.00"-32) Retaining Ring

SM05LTRR

SM05 (0.535"-40) 
Stress-Free Retaining Ring

SM1PRR

SM1 (1.035"-40)
Plastic Retaining Ring

SM75RR

SM75 (M75.5 x 0.5)
Retaining Ring

SM4RR

SM4 (4.035"-40)
Retaining Ring

SM18RR

SM18 (0.750"-40)
Retaining Ring

Related Items

Highlights

  • Standard (Aluminum) Retaining Rings Available for Optics Ranging from Ø5 mm to Ø4"
  • Stress-Free Retaining Rings are Compatible with the SM05, SM1, and SM2 Thread Standards
  • Delrin (Plastic) SM1 Retaining Ring Provides Gentler Contact with Optic Surface

Thorlabs offers a wide selection of Retaining Rings for securing optical components into our threaded mounts, lens tubes, and unmounted optic adapters. Two retaining rings can be used to secure the optical component inside the center of a lens tube: one as a stopper and the other to lock in the component. Depending on the size needed, these retaining rings are available in one or more of the following types: standard (aluminum), stress-free, or plastic (see table below for details).

Our Stress-Free Retaining Rings (SM05LTRR, SM1LTRR, and SM2LTRR) have a rubber O-ring that provides a light-tight seal around the optical components. The SM1PRR Plastic Retaining Ring is produced from Delrin to provide gentler contact with an optic's surfaces than our standard SM1RR retaining ring. Please keep in mind that due to the increased thickness of the stress-free and plastic retaining rings, the thickness of the optic that can be accommodated in the mount may be reduced.

Thorlabs also offers a line of compatible fixed-diameter and adjustable spanner wrenches for rings with diameters ranging from 1/4" to 3" and spanner bits for SM05, SM1, SM2, and SM3 retaining rings. For using multiple thread types in the same setup, please see our extensive line of thread adapters.

Optic SizeThreadStandardStress-FreeDelrin (Plastic)
Ø5 mm M5.5 x 0.5 SM5RR - -
Ø6 mm M6.5 x 0.5 SM6RR - -
Ø7 mm M7.5 x 0.5 SM7RR - -
Ø8 mm M8.5 x 0.5 SM8RR - -
Ø9 mm M9.5 x 0.5 SM9RR - -
Ø10 mm M10.5 x 0.5 SM10RR - -
Ø11 mm M11.5 x 0.5 SM11RR - -
Ø1/2" SM05 (0.535"-40) SM05RR SM05LTRR -
Ø13 mm M13.5 x 0.5 SM13RR - -
Ø14 mm M14.5 x 0.5 SM14RR - -
Ø15 mm M15.5 x 0.5 SM15RR - -
Ø16 mm M16.5 x 0.5 SM16RR - -
Ø17 mm M17.5 x 0.5 SM17RR - -
Ø18 mm 0.750"-40 SM18RR - -
Ø19 mm M19.5 x 0.5 SM19RR - -
- RMS (0.800"-36) RMSRR - -
Ø20 mm M20.5 x 0.5 SM20RR - -
- C-Mount (1.00"-32) CMRR - -
Ø1" SM1 (1.035"-40) SM1RR SM1LTRR SM1PRR
Ø30 mm SM30 (M30.5 x 0.5) SM30RR - -
Ø31 mm M31.5 x 0.5 SM31RR - -
Ø32 mm M32.5 x 0.5 SM32RR - -
Optic SizeThreadStandardStress-FreeDelrin (Plastic)
Ø33 mm M33.5 x 0.5 SM33RR - -
Ø34 mm M34.5 x 0.5 SM34RR - -
Ø35 mm M35.5 x 0.5 SM35RR - -
Ø36 mm M36.5 x 0.5 SM36RR - -
Ø37 mm M37.5 x 0.5 SM37RR - -
Ø1.5" SM1.5 (1.535"-40) SM1.5RR - -
Ø39 mm M39.5 x 0.5 SM39RR - -
Ø40 mm M40.5 x 0.5 SM40RR - -
Ø41 mm M41.5 x 0.5 SM41RR - -
Ø42 mm M42.5 x 0.5 SM42RR - -
Ø43 mm M43.5 x 0.5 SM43RR - -
Ø44 mm M44.5 x 0.5 SM44RR - -
Ø45 mm M45.5 x 0.5 SM45RR - -
Ø46 mm M46.5 x 0.5 SM46RR - -
Ø47 mm M47.5 x 0.5 SM47RR - -
Ø48 mm M48.5 x 0.5 SM48RR - -
Ø2" SM2 (2.035"-40) SM2RR SM2LTRR -
Ø75 mm M75.5 x 0.5 SM75RR - -
Ø3" SM3 (3.035"-40) SM3RR - -
Ø100 mm M100.75 x 0.5 SM100RR - -
Ø4" SM4 (4.035"-40) SM4RR - -
Click the Support Documentation icon document icon or Part Number below to view the available support documentation
Part NumberProduct Description
CMRR Support Documentation CMRR:1.00"-32 Retaining Ring for C-Mount and CS-Mount Lens Mounts and Cameras
RMSRR Support Documentation RMSRR:RMS Retaining Ring for RMS Lens Mounts
SM05LTRR Support Documentation SM05LTRR:SM05 Series Stress-Free Retaining Ring
SM05RR Support Documentation SM05RR:SM05 Retaining Ring for Ø1/2" Lens Tubes and Mounts
SM1.5RR Support Documentation SM1.5RR:SM1.5 Retaining Ring for Ø1.5" Lens Mounts
SM100RR Support Documentation SM100RR:SM100 Retaining Ring for Ø100 mm Mounts
SM10RR Support Documentation SM10RR:SM10 Retaining Ring for Ø10 mm Lens Mounts
SM11RR Support Documentation SM11RR:SM11 Retaining Ring for Ø11 mm Lens Mounts
SM13RR Support Documentation SM13RR:SM13 Retaining Ring for Ø13 mm Lens Mounts
SM14RR Support Documentation SM14RR:SM14 Retaining Ring for Ø14 mm Lens Mounts
SM15RR Support Documentation SM15RR:SM15 Retaining Ring for Ø15 mm Lens Mounts
SM16RR Support Documentation SM16RR:SM16 Retaining Ring for Ø16 mm Lens Mounts
SM17RR Support Documentation SM17RR:SM17 Retaining Ring for Ø17 mm Lens Mounts
SM18RR Support Documentation SM18RR:SM18 Retaining Ring for Ø18 mm Lens Mounts
SM19RR Support Documentation SM19RR:SM19 Retaining Ring for Ø19 mm Lens Mounts
SM1LTRR Support Documentation SM1LTRR:SM1 Series Stress-Free Retaining Ring
SM1PRR Support Documentation SM1PRR:SM1 Plastic Retaining Ring for Ø1" Lens Tubes and Mounts
SM1RR Support Documentation SM1RR:SM1 Retaining Ring for Ø1" Lens Tubes and Mounts
SM20RR Support Documentation SM20RR:SM20 Retaining Ring for Ø20 mm Lens Mounts
SM2LTRR Support Documentation SM2LTRR:SM2 Series Stress-Free Retaining Ring
SM2RR Support Documentation SM2RR:SM2 Retaining Ring for Ø2" Lens Tubes and Mounts
SM30RR Support Documentation SM30RR:SM30 Retaining Ring for Ø30 mm Lens Mounts
SM31RR Support Documentation SM31RR:M31.5 x 0.5 Retaining Ring
SM32RR Support Documentation SM32RR:M32.5 x 0.5 Retaining Ring
Part NumberProduct Description
SM33RR Support Documentation SM33RR:M33.5 x 0.5 Retaining Ring
SM34RR Support Documentation SM34RR:M34.5 x 0.5 Retaining Ring
SM35RR Support Documentation SM35RR:M35.5 x 0.5 Retaining Ring
SM36RR Support Documentation SM36RR:M36.5 x 0.5 Retaining Ring
SM37RR Support Documentation SM37RR:M37.5 x 0.5 Retaining Ring
SM39RR Support Documentation SM39RR:M39.5 x 0.5 Retaining Ring
SM3RR Support Documentation SM3RR:SM3 Retaining Ring for Ø3" Lens Tubes and Mounts
SM40RR Support Documentation SM40RR:M40.5 x 0.5 Retaining Ring
SM41RR Support Documentation SM41RR:M41.5 x 0.5 Retaining Ring
SM42RR Support Documentation SM42RR:M42.5 x 0.5 Retaining Ring
SM43RR Support Documentation SM43RR:M43.5 x 0.5 Retaining Ring
SM44RR Support Documentation SM44RR:M44.5 x 0.5 Retaining Ring
SM45RR Support Documentation SM45RR:SM45 Retaining Ring for Ø45 mm Lens Mounts
SM46RR Support Documentation SM46RR:M46.5 x 0.5 Retaining Ring
SM47RR Support Documentation SM47RR:M47.5 x 0.5 Retaining Ring
SM48RR Support Documentation SM48RR:M48.5 x 0.5 Retaining Ring
SM4RR Support Documentation SM4RR:SM4 Retaining Ring for Ø4" Mounts
SM5RR Support Documentation SM5RR:SM5 Retaining Ring for Ø5 mm Lens Mounts
SM6RR Support Documentation SM6RR:SM6 Retaining Ring for Ø6 mm Lens Mounts
SM75RR Support Documentation SM75RR:SM75 Retaining Ring for Ø75 mm Mounts
SM7RR Support Documentation SM7RR:SM7 Retaining Ring for Ø7 mm Lens Mounts
SM8RR Support Documentation SM8RR:SM8 Retaining Ring for Ø8 mm Lens Mounts
SM9RR Support Documentation SM9RR:SM9 Retaining Ring for Ø9 mm Lens Mounts

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Posted Comments:
Poster:jlow
Posted Date:2014-08-13 08:48:36.0
Response from Jeremy at Thorlabs: Thank you for bringing this to our attention. The correct thread is 0.750"-40 for the SM18RR. We will correct the thread call out on the website.
Poster:schach
Posted Date:2014-08-13 14:01:20.563
Guten Tag, welches Gewinde besitzt der Sicherungsring SM18RR? In der Liste finde ich die Angabe M18,5x0,5, die dazugehörige Angabe in der Zeichnung lautet 0,750-40! Vielen Dank im voraus. Mit freundlichen Grüßen C.Schach
Poster:tcohen
Posted Date:2013-02-06 15:26:00.0
Response from Tim at Thorlabs: The O-Ring is Buna-N. We have updated our presentation to include this information.
Poster:nick
Posted Date:2013-02-01 12:08:06.75
Can you please clarify what the o-ring material is (for product SM05LTRR), as well as its lifetime rating in an ambient environment?
Poster:tcohen
Posted Date:2012-09-18 15:10:00.0
Response from Tim at Thorlabs to Luis: These have a black anodized finish which is typically not suitable for UHV. I will contact you directly to discuss your requirements and provide a quote for a vacuum compatible version.
Poster:lgml1
Posted Date:2012-09-17 16:22:31.0
Hello, this is very useful. I just wish to ask whether any the SM17RR is suitable for being used in ultra high vacuum (I'm designing a customised tuve for holding the lens). Cheers, Luis
Poster:tcohen
Posted Date:2012-07-19 13:04:00.0
Response from Tim at Thorlabs: Thank you for contacting us. This will depend on the lens dimensions and material. Qualitatively, you want to use the minimum amount of torque required to secure the optic as overtightening will induce stress birefringence. That being said, the retaining rings should hold the optic in a much less stressful way at the point of contact than a setscrew for example. Stress-free retaining rings were designed with this in mind. I will contact you directly to continue this conversation.
Poster:sebastien.avila
Posted Date:2012-07-17 10:38:21.0
Hello, What is the tightening torque that should not be exeed while using an SM18RR on a 18mm diameter convex lens? We want to have a standar procedure to mounting these lenses and we need to stablish the maximum torque allowed. Thank you.
Poster:tcohen
Posted Date:2012-06-19 10:55:00.0
Response from Tim at Thorlabs: The external thread specifications for the M15.5-0.5 thread used on our SM15RR are Major Max 15.479, Major Min 15.371, Minor Max 14.938, Minor Min 14.757, Pitch Max 15.155 and Pitch Min 15.065.
Poster:jbowen
Posted Date:2012-06-18 08:51:32.0
I would like to know the thread specification for this part. Please provide the minor, major, and pitch diameters with the minimum and maximum tolerances for each dimension.
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Standard Retaining Rings: Ø5 mm to Ø1/2" (12.7 mm)

  • Standard Retaining Rings for Optics Ranging
    from Ø5 mm to Ø1/2"
  • Compatible with our Optic Mounts and Lens Tubes

Our Standard Retaining Rings, available in sizes to match our optic mounts and lens tubes, are designed to maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.

Item #ThreadThicknessThread SpecsCompatible Spanner WrenchCompatible Optic Mounts
SM5RR M5.5 x 0.5 0.07" (1.7 mm) info SPW801 AD5T or SM1AD5
SM6RR M6.5 x 0.5 0.07" (1.7 mm) info SPW801 AD6T or SM1AD6
SM7RR M7.5 x 0.5 0.07" (1.7 mm) info SPW801 AD7T or SM1AD7
SM8RR M8.5 x 0.5 0.07" (1.7 mm) info SPW801 AD8T or SM1AD8
SM9RR M9.5 x 0.5 0.07" (1.7 mm) info SPW801 AD9T or SM1AD9
SM10RR M10.5 x 0.5 0.07" (1.7 mm) info SPW801 AD10T or SM1AD10
SM11RR M11.5 x 0.5 0.07" (1.7 mm) info SPW801 AD11T or SM1AD11
SM05RR SM05 (0.535"-40) 0.07" (1.7 mm) info SPW603 or SPW801 Any Internally SM05-Threaded Mount
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM5RR Support Documentation
SM5RRSM5 Retaining Ring for Ø5 mm Lens Mounts
$9.50
Today
SM6RR Support Documentation
SM6RRSM6 Retaining Ring for Ø6 mm Lens Mounts
$9.50
Today
SM7RR Support Documentation
SM7RRSM7 Retaining Ring for Ø7 mm Lens Mounts
$9.50
Today
SM8RR Support Documentation
SM8RRSM8 Retaining Ring for Ø8 mm Lens Mounts
$9.50
Today
SM9RR Support Documentation
SM9RRSM9 Retaining Ring for Ø9 mm Lens Mounts
$9.50
Today
SM10RR Support Documentation
SM10RRSM10 Retaining Ring for Ø10 mm Lens Mounts
$9.50
Today
SM11RR Support Documentation
SM11RRSM11 Retaining Ring for Ø11 mm Lens Mounts
$9.50
Today
SM05RR Support Documentation
SM05RRSM05 Retaining Ring for Ø1/2" Lens Tubes and Mounts
$4.00
Today

Standard Retaining Rings: Ø13 mm to Ø1"

  • Standard Retaining Rings for Optics Ranging from Ø13 mm to Ø1"
  • SM-Threaded Retaining Rings are Compatible with our SM Optic Mounts and Lens Tubes
  • Retaining Rings with RMS (0.800"-36) and C-Mount (1.00"-32) Threads Available

Our Standard Retaining Rings, available in sizes to match our optic mounts and lens tubes, are designed to maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.

Our C-Mount-threaded (1.00"-32) retaining ring is ideal for securing optical components into our CMR lens mount and C- or CS-Mount compatible CCD and CMOS cameras. As shown in the photo to the left, these retaining rings are engraved with both the part number and "C-Mount" to distinguish it from our SM-threaded retaining rings.

Item #ThreadThicknessThread SpecsCompatible Spanner WrenchCompatible Optic Mounts
SM13RR M13.5 x 0.5 0.07" (1.7 mm) info SPW801 AD13T or SM1AD13
SM14RR M14.5 x 0.5 0.07" (1.7 mm) info SPW801 AD14T or SM1AD14
SM15RR M15.5 x 0.5 0.07" (1.7 mm) info SPW801 LMR15 (LMR15/M), AD15T, or SM1AD15
SM16RR M16.5 x 0.5 0.08" (2.0 mm) info SPW801 AD16T or SM1AD16
SM17RR M17.5 x 0.5 0.08" (2.0 mm) info SPW801 AD17T or SM1AD17
SM18RR 0.750"-40 0.08" (2.0 mm) info SPW801 LMR18 (LMR18/M), AD18T, or SM1AD18
SM19RR M19.5 x 0.5 0.08" (2.0 mm) info SPW801 AD19T or SM1AD19
RMSRR 0.800"-36 0.07" (2.0 mm) info SPW801 HCS013
SM20RR M20.5 x 0.5 0.08" (2.0 mm) info SPW801 LMR20 (LMR20/M), AD20T, or SM1AD20
CMRR 1.00"-32 0.08" (2.0 mm) info SPW801 CMR (CMR/M)
SM1RR SM1 (1.035"-40) 0.08" (2.0 mm) info SPW606, SPW602, or SPW801 Any Internally SM1-Threaded Mount
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM13RR Support Documentation
SM13RRSM13 Retaining Ring for Ø13 mm Lens Mounts
$9.50
Today
SM14RR Support Documentation
SM14RRSM14 Retaining Ring for Ø14 mm Lens Mounts
$9.50
Today
SM15RR Support Documentation
SM15RRSM15 Retaining Ring for Ø15 mm Lens Mounts
$9.50
Today
SM16RR Support Documentation
SM16RRSM16 Retaining Ring for Ø16 mm Lens Mounts
$9.50
Today
SM17RR Support Documentation
SM17RRSM17 Retaining Ring for Ø17 mm Lens Mounts
$9.50
Today
SM18RR Support Documentation
SM18RRSM18 Retaining Ring for Ø18 mm Lens Mounts
$9.50
Today
SM19RR Support Documentation
SM19RRSM19 Retaining Ring for Ø19 mm Lens Mounts
$9.50
Today
RMSRR Support Documentation
RMSRRRMS Retaining Ring for RMS Lens Mounts
$10.50
Today
SM20RR Support Documentation
SM20RRSM20 Retaining Ring for Ø20 mm Lens Mounts
$9.50
Today
CMRR Support Documentation
CMRR 1.00"-32 Retaining Ring for C-Mount and CS-Mount Lens Mounts and Cameras
$12.00
Today
SM1RR Support Documentation
SM1RRSM1 Retaining Ring for Ø1" Lens Tubes and Mounts
$4.50
Today

Standard Retaining Rings: Ø30 mm to Ø1.5" (38.1 mm)

  • Standard Retaining Rings for Optics Ranging
    from Ø30 mm to Ø1.5"
  • Compatible with our Optic Mounts and Lens Tubes

Our Standard Retaining Rings, available in sizes to match our optic mounts and lens tubes, are designed to maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.

Item #ThreadThicknessThread SpecsCompatible Spanner WrenchCompatible Optic Mounts
SM30RR SM30 (M30.5 x 0.5) 0.08" (2.0 mm) info SPW607 or SPW801 Any Internally SM30-Threaded Mount
SM31RR M31.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD31
SM32RR M32.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD32
SM33RR M33.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD33
SM34RR M34.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD34
SM35RR M35.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD35
SM36RR M36.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD36
SM37RR M37.5 x 0.5 0.08" (2.0 mm) info SPW801 SM2AD37
SM1.5RR SM1.5 (1.535"-40) 0.10" (2.5 mm) info SPW801 LMR1.5 (LMR1.5/M) or SM2AD1.5
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM30RR Support Documentation
SM30RRSM30 Retaining Ring for Ø30 mm Lens Mounts
$11.00
Today
SM31RR Support Documentation
SM31RRM31.5 x 0.5 Retaining Ring
$12.00
Today
SM32RR Support Documentation
SM32RRM32.5 x 0.5 Retaining Ring
$12.00
Today
SM33RR Support Documentation
SM33RRM33.5 x 0.5 Retaining Ring
$12.00
Today
SM34RR Support Documentation
SM34RRM34.5 x 0.5 Retaining Ring
$12.00
Today
SM35RR Support Documentation
SM35RRM35.5 x 0.5 Retaining Ring
$12.00
Today
SM36RR Support Documentation
SM36RRM36.5 x 0.5 Retaining Ring
$12.00
Today
SM37RR Support Documentation
SM37RRM37.5 x 0.5 Retaining Ring
$12.00
Today
SM1.5RR Support Documentation
SM1.5RRSM1.5 Retaining Ring for Ø1.5" Lens Mounts
$9.50
Today

Standard Retaining Rings: Ø39 mm to Ø2" (50.8 mm)

  • Standard Retaining Rings for Optics Ranging
    from Ø39 mm to Ø2"
  • Compatible with our Optic Mounts and Lens Tubes

Our Standard Retaining Rings, available in sizes to match our optic mounts and lens tubes, are designed to maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.

Item #ThreadThicknessThread SpecsCompatible Spanner WrenchCompatible Optic Mounts
SM39RR M39.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD39
SM40RR M40.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD40
SM41RR M41.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD41
SM42RR M42.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD42
SM43RR M43.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD43
SM44RR M44.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD44
SM45RR M45.5 x 0.5 0.10" (2.5 mm) info SPW801 LMR45 (LMR45/M) or SM2AD45
SM46RR M46.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD46
SM47RR M47.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD47
SM48RR M48.5 x 0.5 0.10" (2.5 mm) info SPW801 SM2AD48
SM2RR SM2 (2.035"-40) 0.10" (2.5 mm) info SPW604 or SPW801 Any Internally SM2-Threaded Mount
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM39RR Support Documentation
SM39RRM39.5 x 0.5 Retaining Ring
$12.00
Today
SM40RR Support Documentation
SM40RRM40.5 x 0.5 Retaining Ring
$12.00
Today
SM41RR Support Documentation
SM41RRM41.5 x 0.5 Retaining Ring
$12.00
Today
SM42RR Support Documentation
SM42RRM42.5 x 0.5 Retaining Ring
$12.00
Today
SM43RR Support Documentation
SM43RRM43.5 x 0.5 Retaining Ring
$12.00
Today
SM44RR Support Documentation
SM44RRM44.5 x 0.5 Retaining Ring
$12.00
Today
SM45RR Support Documentation
SM45RRSM45 Retaining Ring for Ø45 mm Lens Mounts
$12.20
3-5 Days
SM46RR Support Documentation
SM46RRM46.5 x 0.5 Retaining Ring
$12.00
Today
SM47RR Support Documentation
SM47RRM47.5 x 0.5 Retaining Ring
$12.00
Today
SM48RR Support Documentation
SM48RRM48.5 x 0.5 Retaining Ring
$12.00
Today
SM2RR Support Documentation
SM2RRSM2 Retaining Ring for Ø2" Lens Tubes and Mounts
$6.75
Today

Standard Retaining Rings: Ø75 mm to Ø4" (Ø101.6 mm)

  • Standard Retaining Rings for Optics Ranging
    from Ø75 mm to Ø4"
  • Compatible with our Optic Mounts and Lens Tubes

Our Standard Retaining Rings, available in sizes to match our optic mounts and lens tubes, are designed to maximize the clear aperture while providing sufficient holding force. Securing an optic using a retaining ring is a stable method for holding the optic since the optic is retained along its entire edge instead of just at a few points. Each retaining ring is machined with two slots for compatibility with our selection of spanner wrenches.

Item #ThreadThicknessThread SpecsCompatible Spanner WrenchCompatible Optic Mounts
SM75RR M75.5 x 0.5 0.16" (4.1 mm) info SPW801a LMR75 (LMR75/M)
SM3RR SM3 (3.035"-40) 0.10" (2.5 mm) info SPW605 or SPW801a Any Internally SM3-Threaded Mount
SM100RR M100.75 x 0.5 0.16" (4.1 mm) info N/A LMR100 (LMR100/M)
SM4RR SM4 (4.035"-40) 0.13" (3.3 mm) info N/A LMR4 (LMR4/M)
  • The blades of the SPW801 will overhang the inner edge of the SM75RR and SM3RR retaining rings. If you wish to mount a lens with a short focal length using one of these retaining rings with the SPW801, please contact Technical Support for additional information.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM75RR Support Documentation
SM75RRSM75 Retaining Ring for Ø75 mm Mounts
$14.30
Today
SM3RR Support Documentation
SM3RRSM3 Retaining Ring for Ø3" Lens Tubes and Mounts
$14.30
Today
SM100RR Support Documentation
SM100RRSM100 Retaining Ring for Ø100 mm Mounts
$16.60
Today
SM4RR Support Documentation
SM4RRCustomer Inspired!SM4 Retaining Ring for Ø4" Mounts
$16.60
3-5 Days

Stress-Free Retaining Rings

Item #ThreadThicknessCompatible
Spanner Wrench
Compatible
Optic Mounts
SM05LTRR SM05 (0.535"-40) 0.15" (3.8 mm) SPW603 or SPW801 Any Internally
SM05-Threaded Mount
SM1LTRR SM1 (1.035"-40) 0.16" (4.1 mm) SPW602 or SPW801 Any Internally
SM1-Threaded Mount
SM2LTRR SM2 (2.035"-40) 0.18" (4.6 mm) SPW604 or SPW801 Any Internally
SM2-Threaded Mount
Stress-Free
Retaining Ring
Clear ApertureStandard
Retaining Ring
Clear Aperture
SM05LTRR Ø0.32" (Ø8.1 mm) SM05RR Ø0.43" (Ø10.9 mm)
SM1LTRR Ø0.82" (Ø20.8 mm) SM1RR Ø0.90" (Ø22.9 mm)
SM2LTRR Ø1.68" (Ø42.7 mm) SM2RR Ø1.90" (Ø48.3 mm)
  • Design Provides Reduced Stress Clamping Action
  • Provides Light-Tight Seal Around an Optic
  • Compatible with our Optic Mounts and Lens Tubes

Our Stress-Free Retaining Rings are available with our standard SM05, SM1, or SM2 threadings. This design uses an O-ring made of Buna-N nitrile rubber to reduce the stress on the optic surface and completely seal out sources of stray light. Like our standard retaining rings, our stress-free retaining rings contain two slots for compatibility with our selection of spanner wrenches.

Due to the rubber O-ring, the clear aperture is slightly reduced relative to our standard retaining rings. Please see the table to the lower right for details.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM05LTRR Support Documentation
SM05LTRRSM05 Series Stress-Free Retaining Ring
$18.40
Today
SM1LTRR Support Documentation
SM1LTRRSM1 Series Stress-Free Retaining Ring
$21.40
Today
SM2LTRR Support Documentation
SM2LTRRSM2 Series Stress-Free Retaining Ring
$23.00
Today

Plastic Retaining Rings

Item #ThreadThicknessCompatible
Spanner Wrench
Compatible
Optic Mounts
SM1PRR SM1 (1.035"-40) 0.11" (2.8 mm)a SPW801 Any Internally
SM1-Threaded Mount
  • Due to the increased thickness of the plastic retaining ring compared to its standard counterpart, the thickness of the optic that can be held in our various SM1-compatible mounts may be decreased.
  • Provides Gentler Contact with an Optic's Surfaces than Standard Retaining Rings
  • Small Through Holes Accommodate SPW801 Adjustable Spanner Wrench

This SM1 Delrin (plastic) Retaining Ring provides gentler contact with the surface of an optic than our standard retaining rings. It is designed for use with our SPW801 Adjustable Spanner Wrench (not compatible with SPW909).

The SM1PRR is thicker than the SM1RR Standard Retaining Ring featured above [0.11" (2.8 mm) compared to 0.08" (2.0 mm)]. Please note that due to the increased thickness, the maximum optic thickness that can be accommodated inside our standard SM1-compatible mounts will be slightly diminished. In addition, the clear aperture of the SM1PRR is slightly reduced relative to the SM1RR [Ø0.80" (Ø20.3 mm) compared to Ø0.90" (Ø22.9 mm)].

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
SM1PRR Support Documentation
SM1PRRCustomer Inspired!SM1 Plastic Retaining Ring for Ø1" Lens Tubes and Mounts
$5.30
Today
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