The Harken 57mm Carbo Ratchet Block w/Becket is a sailboat block designed to control lines and sheets. It features a ratcheting mechanism that allows you to hand-hold lines under load while offering controlled easing without having to use a winch as well as a becket, a mounting point for attatching it to a deck or other fixed location. These small compact blocks have very high working loads for safe, easy trimming.