The Singing Tree Rope Wrench is a new invention designed for climbing and descending a single part of line in a manner that closely mimics the doubled rope technique (DdRT), as commonly practiced by ARBs. This newest version of the Rope Wrench comes from ISC, and is refined w rounded edges, smooth bolts and pins, and the high-end construction you'd expect from ISC. In short, the Rope Wrench is designed to create drag above a rope-tied friction hitch to reduce resistance so that it is comparable to the doubled rope technique (DdRT). wout the Rope Wrench, the amount of grip resulting from a directly tied friction hitch supporting a climber's weight makes controlled descent nearly impossible. The hitch is not only difficult to release, but the heat friction is incredibly high. The Rope Wrench accommodates ONLY "ARB-grade" climbing lines (11-13 mm) interacting w spliced, heat resistant, eye-to-eye prusik cord (8-10 mm) and requires a micropulley/carabiner attachment to the saddle. WARNING: This product requires experience and possibly training in rope-assisted climbing techniques (specifically SRT as described above) and tree-related hazard assessment prior to use. ISC Singing Tree Rope Wrench now Approved for ITCC Competitions.