Crafted from high-quality anodized aluminum with a sleek black finish. Offers a focusing movement range of 5mm, extending from a minimum of 12mm to a maximum of 17mm. Ideal for lenses without a focus ring, providing precise fine-tuning for macro photography. Features a standard M42 mount and is constructed from a lightweight alloy. Compatible with lenses featuring an M42 screw mount or a 42mm screw mount, including telephoto lenses. Can also serve as a macro extension tube. Instructions: Attach the helicoid tube to the lens, then mount the lens and helicoid tube combination onto your camera. This listing is for an adjustable M42 to M42 helicoid focusing lens adapter, with a 12mm-17mm range. Note: Automatic aperture and autofocus will not function correctly with this adapter. Manual focus with exposure metering is supported. Color: Black Material: Aluminum Alloy Package Contents: 1* Adapter (Other products are not included.) Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowable measurement error is +/- 1-3 cm.