Self-tailing winches are ideal for sheets, halyards, and control lines on racing and cruising boats. The self-tailing mechanism means that one crew member can quickly and easily trim or raise sails. The B16ST is a one-speed winch. The handle drives in one direction and ratchets in the other to facilitate cranking under high loads. All others are two-speed self-tailing winches. Two-speed winches enable quick grinding in first gear out of a tack or jibe. When the sheet loads up, the reverse direction gives more power in second gear. All have Harken ôsuper holdingö jaws and one-piece sculpted line guide and peeler. Winches up to the 53 have composite fiber-filled self-tailing jaws that have a gentle angle and tooth design for easy entry and ôsuper holdingö with or without load. Larger winches have aluminum jaws. Four springs ensure that jaws open evenly so line is easy to insert. Tech Info: Drum dia. 4". Base dia. 6 15/16".Height 8 5/16". Weight 17 lbs. Min. line dia.5/16". Max. line dia. 9/16". Line entry height 3 9/16".Gear ratio 1 - 2.5:1. Gear ratio 2 - 9.1:1. Power ratio 1 - 12.4:1. Power ratio 2 - 45.3:1. Fastener circle 5 1/2". Fasteners 5 x 5/16 FH.