As a product expert, I introduce to you the Harken 57mm Carbo Ratchamatic Flip Flop with Cam. This block has a maximum working load of up to 136 kg or 300 lbs, making it suitable for small boats. When under low loads, the block rolls freely in both directions, but engages a ratchet mechanism when the load increases, providing holding power of up to 15:1. The ratchet engagement can also be adjusted to a higher or lower level based on the sailor's strength, sailing style, and system usage. The innovative hinged construction allows for various lead angles, and the block pivots around the line axis, keeping the line close to the deck. With a sheave diameter of 57 mm (2 1/4 in) and a maximum line diameter of 10 mm (3/8 in), this block is versatile and reliable for all your sailing needs.