Feature:1. The focus ring is the best choice for magnifying or altering lenses. It provides a focusing system for lenses without a focusing system.2. It can also be used as a macro tube to provide fine focus control for macro photography.3. Support 3690mm/1.43.5in focusing range, provides a 54mm/2.1in adjustable distance for lens focusing.4. Made of high quality aluminium alloy material, black anodized for longer service life and excellent hand feel. Extinction treatment on the inner side to avoid reflections affecting imaging.5. Adopted M52 and M42 helicoid interface is universal and easy to transfer, make the idle old lens can also be used for digital camera shooting.Specification:Condition: 100% brand newItem type: Focusing Helicoid AdapterMaterial: Aluminium AlloyColor: BlackWeight: Approx. 155g/5.5ozFocusing Range: Approx. 3690mm/1.43.5inInterface: Female Mount: M52 Helicoid MountMale Mount: M42 Helicoid Mount.Package List:1 x Focusing Helicoid Adapter