Locking ring

thingiverse

The locking ring fits over the mounted eyepiece, securing it firmly in place so the rubber won't come loose accidentally. To mount the eyepiece, push it through the ring and position the thick side of the locking ring away from the device. Once installed, press the locking ring flush with the end of the eyepiece to secure the rubber firmly in place. This style fits pvs14 eyepieces perfectly. The locking mechanism holds extremely tight, allowing you to handle the device from the eyepiece without it detaching.