Feature:1. Focusing Range: The focusing range is 1731mm, providing a 14mm adjustment distance for lens focusing.2. Extinction Treatment: The inner wall of the focusing cylinder is subjected to extinction treatment to avoid the impact of reflected light on the imaging.3. Great Choice: It's the great choice for zooming in or changing lenses, providing a focusing system for lenses that don't have a focusing system.4. Premium Materials: Made of aluminum alloy, strong and durable, black anodized for longer life.5. M65 Threaded Interface: Adopt general M65 threaded interface, strong versatility and convenient transfer.Specification:Item Type: Focusing Helicoid AdapterMaterial: Aluminum AlloyColour: BlackFocusing Range: 17-31mmInterface: Male Port: M65 Threaded MountFemale Port: M65 Threaded Mount.Package List:1 xFocusing Helicoid Adapter