High Precision double helical focuser for guider scope / finder scope Interface. The solution for telescopes or telephoto lenses with sluggish focusing. The Focuser has a fixed orientation - so there is no rotation of mounted cameras or eyepieces - or also the field of view with your guide star - when focusing.
 
1.25 inch with M42*0.75 male thread, primary Mirror Interfaces: M31X0.5/M42X0.75