Ideal for use with hand-held loads, Lewmar's control Blocks feature lightweight, performance load-bearing capacity. MRT (Metal Replacement Technology) and a stainless steel central race and balls provide a weight advantage, while Long Fiber Technology offers exceptional strength and durability. The open design allows sand and salt to be flushed out easily, keeping maintenance simple. Description Thru-Deck Single Size 30MM Work Load 440 lbs.