The 0.27 inch (6.9 mm) 9311-K Adjustment Screw provides smooth, wobble-free adjustment combined with exceptional long-term stability and low susceptibility to thermal variation. It is the same 1/4-80 precision screw used in our optic mounts and allows you to build your own mounts or positioners. This mount is 22 mm in total length. In addition, the screw has a ball tip, unbraked brass bushing, and is Hex-key adjusted.