The HSLT1 Lens Tube Heat Sink provides the ability to cool down a lens tube setup that may be subject to an unusual amount of heat. By providing a total surface area of 79 square inches, the HSLT1 provides a thermal resistance of 0.25 °C/W. Ø1" optical components can be mounted into the passive heat sink lens tube using the SM1RR retaining ring (not included) . This Passive Heat Sink lens tube is fully compatible with our SM1 lens tube series and can be easily mounted to any SM1 lens tube setup or to SM05, SM2 or SM3 setups using our lens tube adapters.