Part: C11metBO (black oxide steel)
Fits: Celestron 11” (28 cm) f/10 SCT versions with flat secondary housing and metric collimation screw threads (most CPC 1100). Does not fit the Starizona Hyperstar secondary.
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 (shown in photo) is for dry environments. Lightly oil the knob top and knob serrations periodically as an anti-corrosion measure.
- 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.