1、Focusing Distance: The length of the focusing distance is 25mm (min) to 55mm (maximum), which provides a 30mm adjustment distance for the lens to focusing. 2、Matting Treatment: Matting treatment is done on the inner wall of the focusing cylinder to avoid the impact of reflected light on the imaging, so that the idle old lens can also be used for shooting with digital cameras. 3、M65 Threaded Interface: Focusing tube adopts general M65 threaded interface, which is versatile and easy to transfer. Male M65 threaded Jaws to female M65 threaded Jaws . 4、All Metal: All metal adapter design, made of black anodized, to securely mount the lens, but still be easily removed when not needed. 5、Scope of Application: The focusing ring is the best choice for zooming in or changing the lens, providing a focusing system for lenses without a focusing system.