Lightweight, low profile and very strong, these Carbo AirBlocks® have enormous working range, with a higher working load than standard blocks, even though they are lighter in weight! The Carbo Ratchmatic® is a load-sensing ratchet block that rolls freely in both directions under low loads, and automatically engages the ratchet as loads increase. Shifting between ratchet and light air modes is seamless. Unloaded the sheet runs freely during mark roundings and jibes. Ratchet engagement may be adjusted to a higher or lower load according to strength and sailing style. Holding power of 57 mm is as high as 10:1. Includes a 57mm Triple with becket Carbo Ratchamatic Base and a 57mm Quad boom block, and a 40mm carbo single; line is not included. Safe working load is 1800 pounds; breaking strength is 4500 pounds.