Edelrid Apus Pro Dry 7.9 mm half climbing rope can be used both as a twin and as a half rope. The diameter of 7.9 mm makes it an extremely light rope, perfect for mountaineering. The Thermo Shield treatment makes it supple and manageable without it stiffening prematurely. The Pro Dry, on the other hand, makes the rope waterproof and resistant to dirt, resistant and durable over time. Instructions. Edelrid Apus Pro Dry 7.9 mm climbing half rope