The key to the ease of use of each spool is found in the unique SCUBAPRO branded rotating discs located at the center point of the spool; the discs remain static while the reel turns and the line unwinds. As a result, the reel will not try to rotate out of your hand like regular reels do, allowing for a more secure grip when releasing the line. You can adjust the tension on the line by squeezing the spinner discs together, forming a disc brake effect. Made of durable injection-molded fiberglass-reinforced nylon with a stainless steel axle and screws, the reel body is designed so that it can easily be attached to a snap bolt.