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Retaining Rings


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Retaining Rings

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).

The stress-free versions (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 plastic retaining ring, 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. Additionally, we offer retaining rings for RMS threads and an extensive line of thread adapters.

Optic SizeThreadStandardStress-FreeDelrin (Plastic)
Ø5 mmM5.5 x 0.5SM5RR--
Ø6 mmM6.5 x 0.5SM6RR--
Ø7 mmM7.5 x 0.5SM7RR--
Ø8 mmM8.5 x 0.5SM8RR--
Ø9 mmM9.5 x 0.5SM9RR--
Ø10 mmM10.5 x 0.5SM10RR--
Ø11 mmM11.5 x 0.5SM11RR--
Ø1/2"SM05 (0.535"-40)SM05RRSM05LTRR-
Ø13 mmM13.5 x 0.5SM13RR--
Ø14 mmM14.5 x 0.5SM14RR--
Ø15 mmM15.5 x 0.5SM15RR--
Ø16 mmM16.5 x 0.5SM16RR--
Ø17 mmM17.5 x 0.5SM17RR--
Ø18 mm0.750"-40SM18RR--
Ø19 mmM19.5 x 0.5SM19RR--
Ø20 mmM20.5 x 0.5SM20RR--
Ø1"SM1 (1.035"-40)SM1RRSM1LTRRSM1PRR
Ø30 mmSM30 (M30.5 x 0.5)SM30RR--
Ø31 mmM31.5 x 0.5SM31RR--
Ø32 mmM32.5 x 0.5SM32RR--
Ø33 mmM33.5 x 0.5SM33RR--
Optic SizeThreadStandardStress-FreeDelrin (Plastic)
Ø34 mmM34.5 x 0.5SM34RR--
Ø35 mmM35.5 x 0.5SM35RR--
Ø36 mmM36.5 x 0.5SM36RR--
Ø37 mmM37.5 x 0.5SM37RR--
Ø1.5"1.535"-40SM1.5RR--
Ø39 mmM39.5 x 0.5SM39RR--
Ø40 mmM40.5 x 0.5SM40RR--
Ø41 mmM41.5 x 0.5SM41RR--
Ø42 mmM42.5 x 0.5SM42RR--
Ø43 mmM43.5 x 0.5SM43RR--
Ø44 mmM44.5 x 0.5SM44RR--
Ø45 mmM45.5 x 0.5SM45RR--
Ø46 mmM46.5 x 0.5SM46RR--
Ø47 mmM47.5 x 0.5SM47RR--
Ø48 mmM48.5 x 0.5SM48RR--
Ø2"SM2 (2.035"-40)SM2RRSM2LTRR-
Ø75 mmM75.5 x 0.5SM75RR--
Ø3"SM3 (3.035"-40)SM3RR--
Ø100 mmM100.75 x 0.5SM100RR--
Ø4"4.035"-40SM4RR--

SM Series Threading Specifications

Thorlabs' lens tubes utilize a series of non-standard threadings. Threading specifications are given below for our SM threadings utilized in our lens tube and cage system components so that you can machine mating components to suit your application. For threading specifications other than what is listed here, please contact Tech Support.

SM05 Threading: Ø1/2" Lens Tubes, 16 mm Cage Systems
External Thread, 0.535"-40.0, UNS-2AInternal Thread, 0.535"-40.0, UNS-2B
Max Major Diameter0.5340"Min Major Diameter0.5350"
Min Major Diameter0.5289"Min Pitch Diameter0.5188"
Max Pitch Diameter0.5178"Max Pitch Diameter0.5230"
Min Pitch Diameter0.5146"Min Minor Diameter (and 83.3% of thread)0.508"
Max Minor Diameter0.5069"Max Minor Diameter (and 64.9% of thread)0.514"
SM1 Threading: Ø1" Lens Tubes, 30 mm Cage Systems
External Thread, 1.035"-40.0, UNS-2AInternal Thread, 1.035"-40.0, UNS-2B
Max Major Diameter1.0339"Min Major Diameter1.0350"
Min Major Diameter1.0288"Min Pitch Diameter1.0188"
Max Pitch Diameter1.0177"Max Pitch Diameter1.0234"
Min Pitch Diameter1.0142"Min Minor Diameter (and 83.3% of thread)1.008"
Max Minor Diameter1.0068"Max Minor Diameter (and 64.9% of thread)1.014"
SM30 Threading: Ø30 mm Lens Tubes
External Thread, M30.5x0.5Internal Thread, M30.5x0.5
Max Major Diameter30.480 mmMin Major Diameter30.500 mm
Min Major Diameter30.371 mmMin Pitch Diameter30.175 mm
Max Pitch Diameter30.155 mmMax Pitch Diameter30.302 mm
Min Pitch Diameter30.059 mmMin Minor Diameter (and 83.3% of thread)29.959 mm
Max Minor Diameter29.938 mmMax Minor Diameter (and 64.9% of thread)30.094 mm
SM2 Threading: Ø2" Lens Tubes, 60 mm Cage Systems
External Thread, 2.035"-40.0, UNS-2AInternal Thread, 2.035"-40.0, UNS-2B
Max Major Diameter2.0338"Min Major Diameter2.0350"
Min Major Diameter2.0287"Min Pitch Diameter2.0188"
Max Pitch Diameter2.0176"Max Pitch Diameter2.0239"
Min Pitch Diameter2.0137"Min Minor Diameter (and 83.3% of thread)2.008"
Max Minor Diameter2.0067"Max Minor Diameter (and 64.9% of thread)2.014"
SM3 Threading: Ø3" Lens Tubes
External Thread, 3.035"-40.0, UNS-2AInternal Thread, 3.035"-40.0, UNS-2B
Max Major Diameter3.0337"Min Major Diameter3.0350"
Min Major Diameter3.0286"Min Pitch Diameter3.0188"
Max Pitch Diameter3.0175"Max Pitch Diameter3.0242"
Min Pitch Diameter3.0133"Min Minor Diameter (and 83.3% of thread)3.008"
Max Minor Diameter3.0066"Max Minor Diameter (and 64.9% of thread)3.014"

Thorlabs' Stackable Lens Tubes provide an easy and fast solution for assembly of an optical system with a single optical axis. Using lens tubes one can easily assemble several optical components on a common optical axis without the need for X-Y alignment of each component to the common axis. Thorlabs offers Ø1/2”, Ø1”, Ø2” and Ø3” lens tubes, for use with different optics sizes, as well as adapters to convert between the four different sizes.

Lens Tubes Application Example

Thorlabs also offers many of our optical components in pre-mounted 1” lens tubes as well as specially developed components and mounts, all of which are pre-aligned to the optical axis, including:

Thorlabs has also added alignment tools for lens tubes for working with IR optics, such as infrared alignment disks and alignment targets. Additionally, with the use of retaining rings, any standard optical component can be easily mounted into the lens tubes.

For more complex optical systems Thorlabs has developed sets of post mounting rings, mounting brackets, and construction cubes to enable building complex, rugged systems.

Thorlabs lens tubes can also easily interface with our cage system components such as the cage plates, kinematic turning mirror mounts, pre-mounted beamsplitter cubes and pre-mounted turning mirrors.

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Posted Comments:
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)
Item # Thread Thickness Compatible
Spanner Wrench
Compatible
Optic Mounts
SM5RR M5.5 x 0.5 0.07" (1.7 mm) SPW801 AD5T or SM1AD5
SM6RR M6.5 x 0.5 0.07" (1.7 mm) SPW306 or SPW801 AD6T or SM1AD6
SM7RR M7.5 x 0.5 0.07" (1.7 mm) SPW801 AD7T or SM1AD7
SM8RR M8.5 x 0.5 0.07" (1.7 mm) SPW308 or SPW801 AD8T or SM1AD8
SM9RR M9.5 x 0.5 0.07" (1.7 mm) SPW301 or SPW801 AD9T or SM1AD9
SM10RR M10.5 x 0.5 0.07" (1.7 mm) SPW801 AD10T or SM1AD10
SM11RR M11.5 x 0.5 0.07" (1.7 mm) SPW801 AD11T or SM1AD11
SM05RR SM05 (0.535"-40) 0.07" (1.7 mm) SPW603 or SPW801 Any Internally
SM05-Threaded Mount
  • 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.

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
SM5RR SM5 Retaining Ring for Ø5 mm Lens Mounts
$9.50
Today
SM6RR Support Documentation
SM6RR SM6 Retaining Ring for Ø6 mm Lens Mounts
$9.50
Today
SM7RR Support Documentation
SM7RR SM7 Retaining Ring for Ø7 mm Lens Mounts
$9.50
Today
SM8RR Support Documentation
SM8RR SM8 Retaining Ring for Ø8 mm Lens Mounts
$9.50
Today
SM9RR Support Documentation
SM9RR SM9 Retaining Ring for Ø9 mm Lens Mounts
$9.50
Today
SM10RR Support Documentation
SM10RR SM10 Retaining Ring for Ø10 mm Lens Mounts
$9.50
Today
SM11RR Support Documentation
SM11RR SM11 Retaining Ring for Ø11 mm Lens Mounts
$9.50
Today
SM05RR Support Documentation
SM05RR SM05 Retaining Ring for Ø1/2" Lens Tubes and Mounts
$4.00
Today
Standard Retaining Rings: Ø13 mm to Ø1"
Item # Thread Thickness Compatible
Spanner Wrench
Compatible
Optic Mounts
SM13RR M13.5 x 0.5 0.07" (1.7 mm) SPW801 AD13T or SM1AD13
SM14RR M14.5 x 0.5 0.07" (1.7 mm) SPW801 AD14T or SM1AD14
SM15RR M15.5 x 0.5 0.07" (1.7 mm) SPW801 LMR15 (LMR15/M),
AD15T, or SM1AD15
SM16RR M16.5 x 0.5 0.08" (2.0 mm) SPW801 AD16T or SM1AD16
SM17RR M17.5 x 0.5 0.08" (2.0 mm) SPW801 AD17T or SM1AD17
SM18RR 0.750"-40 0.08" (2.0 mm) SPW801 LMR18 (LMR18/M),
AD18T, or SM1AD18
SM19RR M19.5 x 0.5 0.08" (2.0 mm) SPW801 AD19T or SM1AD19
SM20RR M20.5 x 0.5 0.08" (2.0 mm) SPW801 LMR20 (LMR20/M),
AD20T, or SM1AD20
SM1RR SM1 (1.035"-40) 0.08" (2.0 mm) SPW606, SPW602,
or SPW801
Any Internally
SM1-Threaded Mount
  • Standard Retaining Rings for Optics Ranging from Ø13 mm to Ø1"
  • 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.

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
SM13RR SM13 Retaining Ring for Ø13 mm Lens Mounts
$9.50
Today
SM14RR Support Documentation
SM14RR SM14 Retaining Ring for Ø14 mm Lens Mounts
$9.50
Today
SM15RR Support Documentation
SM15RR SM15 Retaining Ring for Ø15 mm Lens Mounts
$9.50
Today
SM16RR Support Documentation
SM16RR SM16 Retaining Ring for Ø16 mm Lens Mounts
$9.50
Today
SM17RR Support Documentation
SM17RR SM17 Retaining Ring for Ø17 mm Lens Mounts
$9.50
Today
SM18RR Support Documentation
SM18RR SM18 Retaining Ring for Ø18 mm Lens Mounts
$9.50
Today
SM19RR Support Documentation
SM19RR SM19 Retaining Ring for Ø19 mm Lens Mounts
$9.50
Today
SM20RR Support Documentation
SM20RR SM20 Retaining Ring for Ø20 mm Lens Mounts
$9.50
Today
SM1RR Support Documentation
SM1RR SM1 Retaining Ring for Ø1" Lens Tubes and Mounts
$4.50
Today
Standard Retaining Rings: Ø30 mm to Ø1.5" (38.1 mm)
Item # Thread Thickness Compatible
Spanner Wrench
Compatible
Optic Mounts
SM30RR SM30 (M30.5 x 0.5) 0.08" (2.0 mm) SPW607 or SPW801 Any Internally
SM30-Threaded Mount
SM31RR M31.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD31
SM32RR M32.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD32
SM33RR M33.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD33
SM34RR M34.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD34
SM35RR M35.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD35
SM36RR M36.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD36
SM37RR M37.5 x 0.5 0.08" (2.0 mm) SPW801 SM2AD37
SM1.5RR 1.535"-40 0.10" (2.5 mm) SPW801 LMR1.5 (LMR1.5/M) or
SM2AD1.5
  • 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.

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
SM30RR SM30 Retaining Ring for Ø30 mm Lens Mounts
$11.00
Today
SM31RR Support Documentation
SM31RR SM31 Retaining Ring for Ø31 mm Lens Mounts
$12.00
Today
SM32RR Support Documentation
SM32RR SM32 Retaining Ring for Ø32 mm Lens Mounts
$12.00
Today
SM33RR Support Documentation
SM33RR SM33 Retaining Ring for Ø33 mm Lens Mounts
$12.00
Today
SM34RR Support Documentation
SM34RR SM34 Retaining Ring for Ø34 mm Lens Mounts
$12.00
Today
SM35RR Support Documentation
SM35RR SM35 Retaining Ring for Ø35 mm Lens Mounts
$12.00
Today
SM36RR Support Documentation
SM36RR SM36 Retaining Ring for Ø36 mm Lens Mounts
$12.00
Today
SM37RR Support Documentation
SM37RR SM37 Retaining Ring for Ø37 mm Lens Mounts
$12.00
Today
SM1.5RR Support Documentation
SM1.5RR SM1.5 Retaining Ring for Ø1.5" Lens Mounts
$9.50
Today
Standard Retaining Rings: Ø39 mm to Ø2" (50.8 mm)
Item # Thread Thickness Compatible
Spanner Wrench
Compatible
Optic Mounts
SM39RR M39.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD39
SM40RR M40.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD40
SM41RR M41.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD41
SM42RR M42.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD42
SM43RR M43.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD43
SM44RR M44.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD44
SM45RR M45.5 x 0.5 0.10" (2.5 mm) SPW801 LMR45 (LMR45/M) or
SM2AD45
SM46RR M46.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD46
SM47RR M47.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD47
SM48RR M48.5 x 0.5 0.10" (2.5 mm) SPW801 SM2AD48
SM2RR SM2 (2.035"-40) 0.10" (2.5 mm) SPW604 or SPW801 Any Internally
SM2-Threaded Mount
  • 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.

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
SM39RR SM39 Retaining Ring for Ø39 mm Lens Mounts
$12.00
Today
SM40RR Support Documentation
SM40RR SM40 Retaining Ring for Ø40 mm Lens Mounts
$12.00
Lead Time
SM41RR Support Documentation
SM41RR SM41 Retaining Ring for Ø41 mm Lens Mounts
$12.00
Today
SM42RR Support Documentation
SM42RR SM42 Retaining Ring for Ø42 mm Lens Mounts
$12.00
Today
SM43RR Support Documentation
SM43RR SM43 Retaining Ring for Ø43 mm Lens Mounts
$12.00
Today
SM44RR Support Documentation
SM44RR SM44 Retaining Ring for Ø44 mm Lens Mounts
$12.00
Today
SM45RR Support Documentation
SM45RR SM45 Retaining Ring for Ø45 mm Lens Mounts
$12.20
Today
SM46RR Support Documentation
SM46RR SM46 Retaining Ring for Ø46 mm Lens Mounts
$12.00
Today
SM47RR Support Documentation
SM47RR SM47 Retaining Ring for Ø47 mm Lens Mounts
$12.00
Today
SM48RR Support Documentation
SM48RR SM48 Retaining Ring for Ø48 mm Lens Mounts
$12.00
Today
SM2RR Support Documentation
SM2RR SM2 Retaining Ring for Ø2" Lens Tubes and Mounts
$6.75
Today
Standard Retaining Rings: Ø75 mm to Ø4" (Ø101.6 mm)
Item # Thread Thickness Compatible
Spanner Wrench
Compatible
Optic Mounts
SM75RR M75.5 x 0.5 0.16" (4.1 mm) SPW801a LMR75 (LMR75/M)
SM3RR SM3 (3.035"-40) 0.10" (2.5 mm) SPW605 or SPW801a Any Internally
SM3-Threaded Mount
SM100RR M100.75 x 0.5 0.16" (4.1 mm) N/A LMR100 (LMR100/M)
SM4RR 4.035"-40 0.13" (3.3 mm) 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.
  • 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.

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
SM75RR SM75 Retaining Ring for Ø75 mm Mounts
$14.30
Today
SM3RR Support Documentation
SM3RR SM3 Retaining Ring for Ø3" Lens Tubes and Mounts
$14.30
Today
SM100RR Support Documentation
SM100RR SM100 Retaining Ring for Ø100 mm Mounts
$16.60
Today
SM4RR Support Documentation
SM4RR Customer Inspired! SM4 Retaining Ring for Ø4" Mounts
$16.60
Today
Stress-Free Retaining Rings
Item # Thread Thickness Compatible
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 Aperture Standard
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
SM05LTRR SM05 Series Stress-Free Retaining Ring
$18.40
Today
SM1LTRR Support Documentation
SM1LTRR SM1 Series Stress-Free Retaining Ring
$21.40
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SM2LTRR Support Documentation
SM2LTRR SM2 Series Stress-Free Retaining Ring
$23.00
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Plastic Retaining Rings
Item # Thread Thickness Compatible
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
SM1PRR Customer Inspired! SM1 Plastic Retaining Ring for Ø1" Lens Tubes and Mounts
$5.30
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