Pre-Drilled Mounting Holes Anodized Aluminum Color-Matched in Celestron Orange Designed specifically for 9.25″ and 11″ Celestron Schmidt-Cassegrain (SCT) and HD Cassegrain telescopes, the Alpine Astronomical 17.9″ Vixen Dovetail Rail has pre-drilled mounting holes that match those on the scope. Made of lightweight and durable aluminum, the rail is treated with an anodized finish that is color matched to the optical tube assembly (OTA) in the iconic Celestron orange.