Astromania Schmidt-Cassegrain Finder Scope Base fits factory drilled holes on Celestron, Meade, and Orion Schmidt-Cassegrain telescopes, attaches directly to Schmidt-Cassegrain Telescope (SCT) optical tube with included mounting hardware. Allows you to attach any standard finder scope, Laser Pointer bracket or reflex sight bracket to Schmidt-Cassegrain telescopes (SCT) up to 11 inch aperture, great for second or third aiming device to your Schmidt-Cassegrain for multiple aiming options. Made of high strength Aluminum with Anodizing Aluminium Process. The base is made of die-cast metal and features one large thumbscrew locks. Includes two M4 screws. Synta-style dovetail base -- Fit most bracket designs from Celestron, Orion, Sky-watcher, Vixen, etc. Compliable with finder scope, Laser Pointer bracket on telescopes. The clamp in the bottom of dovetail base is fit standard Vixen dovetail bar. Drilled (but not threaded) to accommodate screws up to 4mm in diameter. Center-to-center screw hole spacing on your telescope must be from 21 to 37.3mm in order for this dovetail base to be compatible.