Knobs for Orion's SkyQuest XT-Series (6", 8", 10", 12",Â and 16") 4-Vane Phillips Screw Secondary - 25 mm Long.Fits:Â OrionÂ SkyQuest XT-series with factory 25 mm long Phillips secondary collimation screws. This configuration is not as common as the set-screw secondary.Secondary Characteristics:Â 4-vane spider, a deeply recessed center screw, and factory Phillips collimation screws. The secondary plate holding the screws is about 20 mm (3/4") thick.Knobs:Â Black plastic, 13 mm (1/2") diameterThreads:Â Stainless steelNotes:
The factory collimation screw length, measured below the head, can be either 25 mm or 32 to 35 mm long. Order knobs with the correct screw length for your application.