Bob's Knobs for Celestron SCT 11” f/10 Standard Fastar: Enhance Telescope Adjustability Designed for Celestron SCT 11" f/10 Fastar: Ideal for Celestron 11” (28 cm) f/10 SCT models with standard thread factory collimation screws and "Trifid" rotary cover Fastar secondary housing. Part Information - Part: C11stdfst: Telescope Compatibility: Fits Celestron 11” SCTs (metal or carbon fiber tube) with standard threads, including models with Starizona Hyperstar (if they have standard threads). Knob Features: Constructed from black plastic, each knob is 16 mm (5/8”) in diameter, designed for easy and precise adjustments. Thread Material: Equipped with stainless steel threads for durability and a perfect match. Thread Type Guidance: Identifying Screw Threads: Silver Phillips screws typically indicate standard threads. Some black Phillips screws may also be standard. Use our hints to determine the correct thread type. Return and Exchange Policy: If knobs with incorrect threads are ordered, they can be returned for a refund. Options to order both standard and metric thread screws are available, with the ability to return the unused set. Factory Dust Cover Compatibility: Normal Dust Cover Fit: Ensures the factory dust cover will continue to fit as usual with Bob’s Knobs installed. Rotary Secondary Cover Instructions: Cover Positioning: The rotary secondary cover must stay open when knobs are installed, as it's purely cosmetic and does not impact the telescope's operation. User-Friendly Telescope Tuning: Perfect for Celestron SCT 11” f/10 Fastar telescope owners looking for an efficient, tool-free method for precise collimation adjustments.