A simple descender device, the Petzl Huit Descender can be used with single or double ropes and is square-shaped to help prevent twisting. The small hole can also be used for small diameter ropes to increase friction and control. Petzl Huit Fig 8 Descender Specifications: Material(s): aluminum Weight: 100 g Rope compatibility: for use on 8 - 13 mm diameter ropes