a preferably palm - sized cleat which is generally oval in shape defines a passageway for a line to pass completely through the body of the cleat . the body of the cleat has mutually resilient sides which bias internal structure in the body into a locked mode in which the line is gripped by the internal structure and will not slide through the passage way . when the sides of the body are squeezed together , the line is freed and will move freely in either direction through the passageway .