Keep an extra RC4 style quick release plate on hand, you never know when you will need one. This plate provides a large lens with additional support and stability. To release, the release button must be pressed and held while the lever is moved to the unlocked position. This replaces the Manfrotto 3271. The plate is shipped with 3/8" and 1/4" screw for your camera/lens mount. Two bubble levels are mounted into the RC4 base plate--one on the side and the other on the top. This will indicate level regardless of whether the lens/camera is vertical or horizontal.