The NEW Petzl twin hand rope ascenders are used to ascend your climbing line. Aluminum with large eronomic molded handles. Holes in top and bottom for carabiner attachment to lanyards and ropes. Works on 1/2" ropes only. Locks in one direction when loaded and pushes easily in other direction when not loaded. Breaking strength - 6 Kn - 12 Kn Weight 1 lb.