2" Low 20mm profile helical Newtonian focuser, 1.25" adapter. One turn travels 0.125" (3mm); this gives just as good control as any 2-speed focuser. Backlash under 0.002"
Go low! A lower profile for a Newtonian focuser means you can use a smaller diagonal and get more illumination of the Airy disc. The FOCH is a rotating universal base, 8TPI helical focuser with low focus of 20mm (with part NPA low focus is close to zero). Includes 1.25" adapter. Useable with a flat base.