Harken Carbo Air blocks are made of tough reinforced composite in a size and style to fit any system: singles, doubles, triples, quads & quints; ratchets and fiddles; soft and hard attach. They have very high working loads for safe, easy trimming and are lightweight, strong, reliable and affordable. Carbo ratchet blocks allow sailors to hand-hold loaded lines and offer balance between holding power and controlled easing. The 57mm switchable ratchets provide precise on/off control with accessible, easy-to-operate switches on both sides of the block. Nylon resin sideplates are densely packed with long-glass fibers for a compact block with a high strength-to-weight ratio. Machined aluminum sheaves are hardcoat anodized for strength and corrosion resistance. Eight facets hold the line securely. Ball bearings, sheave, and sideplates are UV-stabilized.