Harken 57mm Ratchet Carbo, Double, with Swivel - #2178Carbo ratchet blocks allow sailors to hand hold loaded lines and offer balance between holding power and controlled easing. Machined aluminum sheaves are Hard Lube anodized for strength and corrosion resistance. Eight facets hold line securely. Switchable ratchets provide precise control with an accessible on off switch that is easy to operate from both sides of the block.