Harken 57 mm & 75 mm Carbo Ratchets Hand hold loaded lines and control release using 57 and 75 mm Carbo Ratchets. Machined aluminum sheaves have eight facets to hold line securely. The 75 mm provides up to 15:1 holding power and the 57 mm 10:1. Choose switchable ratchets for on/off control. For the ultimate 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. Use for: Main/jib sheets Spinnaker sheets Traveler controls Foreguys