Feature:1. Made of quality aluminium alloy material, high strength, corrosion resistant, sturdy and durable.2. Lightweight and compact size, easy to carry and use.3. High precision double helical focuser for guider scope/finder scope Interface.4. The solution for telescopes or telephoto lenses with sluggish focusing.5. Wonderful accessory for astronomical telescope.Specification:Item type: Double Helical FocuserCondition: 100% brand newMaterial: aluminium alloyWeight: Approx. 120gColor: As picture shownFocusing Stroke: Approx. 10mm/0.4inAccuracy of focusing: Approx. 0.05mmInterface: 1.25inches, inner M42*0.75mm thread1.25'' helical focuser, 10mm focusing stroke, lightweight. In the process of focusing, the inserted eyepiece or zenith, etc. keeps no rotation and only makes linear motion, which is conducive to observation and shooting..Package List:1 x Helical Focuser