The QS-48PF Quick Release Adapter is a replacement part for the SBH-250 andSBH-300 Ball Heads. It consists of the base and quick release plate. The base has a locking knob and a safety lock to make sure the plate will not be released accidentally. Two bubble levels are located on the base for aligning your camera to the horizon. The quick release plate has both 1/4"-20 and 3/8"-16 camera screws and a video pin. The base attaches to the ball head with an included 3/8"-16 Allen Bolt.