Carbo ratchets represent a new line of on/off switchable 57mm and 75mm ratchets, available in multiple configurations, for all ratchet applications on dinghies and keelboats. They feature lightweight nylon resin sideplates, densely packed with long glass fibers, to replace stainless steel reinforcing straps. The fibers align with block contours for superior strength.For the ultimate mainsheet system, mount a switchable ratchet in the cockpit and a boom-mounted Ratchamatic directly above to allow double holding power in heavy air and to ensure the mainsheet runs freely in light air. Perfect for hand holding loaded lines with controlled release The 57mm ratchet provides sailors with up to 10:1 additional holding power Accessible and easy-to-operate on/off switches (found in the center airhole) on both sides of the block Machined Hardkote-anodized aluminum sheaves have eight facets to hold line securely Sheave diameter: 2-1/4" (57mm) Maximum line size: 3/8" (57mm)