This is the Akona Plastic Finger Spool with Double Ended Snap Bolt Clip Features: Includes double ended clip Stainless steel clips High Visibility Orange Color Line Ideal for cave and wreck dicing, scuba diving, the travelling diver, snorkeling, photography, and other underwater activities Dive spools are an essential item when exploring wrecks, caverns/caves, search and recovery, or releasing a delayed SMB. Spools area diver&&';;s safety line. Spools and lines are a tried and true way for divers to return to their starting point. Simply anchor your line to a point just outside the cave opening or at the entrance point of the wreck and unroll your line from the spool as you progress through the dive.