Please note: This text was taken directly from the manufacturer.
Upgrade your Orion reflector with a quality 2" Crayford-style focuser. Designed to replace 2" rack-and-pinion focusers on Orion telescopes, the Crayford-style focuser provides an unmatched level of focusing smoothness and precision. This deluxe cast-aluminum focuser provides super-smooth roller bearing motion, zero image shift, machined metal knobs, and a tension adjustment control. It has a racked-in height of 2-11/16" and 1.4" (35mm) of drawtube travel. It's internally blackened for greater contrast. Accepts 2" and 1.25" eyepieces. The 2" Crayford focuser has the identical mounting hole pattern and spacing as the 2" rack-and-pinion focuser on older Orion 8"- to 12" Dobsonians (except the XT8 Classic) and other 8" and 10" reflector tubes, so no new holes have to be drilled. NOTE: For 203mm (8") f/4.9 and 254mm (10") f/4.7 Orion reflectors, a #5122 adapter is needed to reach focus. T-thread camera adapter (#5117) sold separately.