Knobs: Black oxide steel (black), 12 mm (1/2”) diameter
Threads: Black oxide
- Black Phillips factory collimation screws usually have metric threads, but some black Phillips screws have standard threads. Make sure the knob threads match the factory screw threads before installing the knobs.
- Black oxide steel is for dry environments. Lightly oil the knob top and knob serrations periodically as an anti-corrosion measure.
- These knobs sit inside the tall lip around the perimeter of the secondary, so they may be hard to grasp with two fingers. Adjustments can be made using a thumb or finger against the inside edge of the knob.
- If your telescope has the “Trifid” Fastar rotary cover, these knobs will not fit.
- The factory dust cover will fit normally with Bob's Knobs installed.
- If your telescope has a factory-installed plastic cap over the collimation screws, it must be removed and set aside when Bob's Knobs are installed. The cover is cosmetic only and will not affect operation of the scope.