Plastic (with the exception of the EP holder set screw and the pinion shaft) unused smooth focuser. Flange inside diameter of 85.5mm and outside diameter of 89.7mm. Your standard 1-1/4" eyepiece stays firmly in place with locking screw. Get this if you need an inexpensive replacement or to build your own refractor telescope. Good match for our L3946 and L3947 mounted objectives. Unused.