Bobs Knobs Astro Tech AT6RC & AT8RC Collimation Knobs Secondary Mirror AT8RC

This came with two sets of three threaded knobs: a shorter set, and a longer set.In my at8rc, the shorter knobs were too short to touch the secondary mirror. However, the longer set works great.I was able to roughly collimate my OTA during the day in about 30 seconds, and then precisely collimate the telescope at night once I set it to track Vega. By looking into the eyepiece and reaching into the front of the OTA, I was able to see the shadow of my hand, and easily collimate the telescope in the dark.