Thorlabs' SM05 threaded lens tubes are designed to hold Ø1/2" (Ø12.7 mm) optics. The SM05 threading is compatible with many of our mechanics, allowing customers to easily build complex setups. For example, our 16 mm Cage System utilizes SM05 threading. An extensive line of SM05 threaded accessories are available such as optic mounts, irises, and collimation mounts. Many of our Ø1/2" mounted optics come in SM05 threaded housings.