CMC Rescue - Survivor™ 8 - 300875 Machined out of 3/8-inch (9.5-mm) aluminum stock, this compact figure 8 descender works well with escape lines or other small diameter ropes where minimum size and weight are the primary requirements. The rounded edges reduce sharp bends. The large carabiner hole accepts a wide variety of carabiners and helps prevent binding. The Survivor 8 features a hard anodized finish in a dark gray for users who require a non-reflective surface. * Certified range of rope diameters and CMC’s recommendation for best performance.