The ZK2 Singing Tree Rope Wrench is a unique friction control device designed to work in conjunction with a suitable friction hitch to allow aerial arborists to ascend, descend and work position on a 'single line'. Without the Singing Tree Rope Wrench the friction hitch would bind up on a single rope and not function efficiently. By attaching the Singing Tree Rope Wrench to your system with a stiff tether the device works by applying leverage to force the climbing line into an S-bend above the hitch - the kink in the rope provides additional friction during descent to ensure the knot behaves correctly. You should have a strong working knowledge of Single Line Work Positioning before you attempt to use the Rope Wrench - this means you should have received qualified training! Do not climb above your anchor point!