Special Note: The Celestron 11” SCT uses either standard 6-32 or metric M3 collimation screws.
Allen and set-style factory collimation screws have standard threads.
For Phillips collimation screws, most silver screws are standard and most black screws are metric.
Fits: Celestron 11” (28 cm) f/10 SCT versions (metal or carbon fiber tube) with "Trifid" rotary cover Fastar secondary housing and standard collimation screw threads.
These knobs will also fit the C11 with Starizona Hyperstar .
(Not for EdgeHD or CPC1100)