Knobs for SkyWatcher Newtonian Secondary

Bob's Knobs: Collimate your Schmidt-Cassegrain or Newton-Telescope without tools! It's easy! Just grab a Bob's Knob collimation thumbscrew and turn. You can even do it while looking through the eyepiece on most scopes. And you'll never drop that pesky little Allen wrench or screwdriver into the grass again. Installation is a snap with the included instructions, and you can undo the modification at any time.

Knobs: Black plastic, 13 mm (1/2”) diameter
Threads: Stainless steel, 30mm