The Harken 75mm Ratchamatic Block Swivel, Becket is a load-sensing ratchet block that freely rolls in both directions under low loads and automatically engages the ratchet as loads increase. Transitioning between the ratchet and light-air modes is smooth and seamless. With a maximum line diameter of 12mm and a working load of 341kg, this block is a reliable and efficient choice for any sailing adventure.