The SmallRig BSL2361 is a tripod mount ring for the Canon EF 70-200mm f/2.8L IS II USM and EF 70-200mm f/2.8L IS III USM lenses. It reduces stress on the lens mount and provides stable shooting when attaching these heavy telephoto lenses to a tripod. Arca-Swiss Compatible Plate: The bottom is an Arca-Swiss compatible plate, allowing for quick attachment to compatible tripod heads. Quick Release: Features a quick-release function that allows you to quickly detach the ring and lens from the base plate. Lens Rotation: By loosening the side locking knob, you can rotate the lens around its axis, easily switching between vertical and horizontal positions. Lens Protection: The inside of the ring has a rubber pad to prevent scratches on the lens body. Comfortable Grip: Features a wooden grip that is easy to hold when carrying. Various Mounting Options: Also equipped with 1/4"-20 and 3/8"-16 screw holes to accommodate tripods that are not Arca-Swiss compatible. This product is an accessory designed to reduce stress on the camera mount and improve shooting stability and operability when using heavy telephoto lenses. This is a used item, so there is a feeling of use. Please check the condition in the photos.