A trapeze shock cord is an absolute necessity because it keeps the trapeze system in place and ready for hook-up. One hook connects to either the thimble on the trapeze wire or the adjustment line, then runs under the tramp and connects to the other side in the same location. A plastic carbine hook is installed on one end only; the other hook is included to be installed after the shock cord is put on the boat. Cord is 1/4" diameter by 9′. Each.