Harken 57mm Carbo Single Ratchet Block w/Swivel Becket [2136]57mm Carbo Single Ratchet Block with Swivel & Becket Carbo Ratchets allow sailors to hand hold loaded lines and offer balance between holding power and controlled easing. Features: Sheave (mm): 57 mm Sheave (in): 2 1 4 in Maximum line (mm): 10 mm Maximum line (in): 3 8 in Maximum working load (kg): 227 kg Maximum working load (lb): 500 lb