The Singing Tree Rope Wrench (STRW) is used to create a ‘bend’ in the rope, above the climber’s hitch. With the addition of a stiff tether, the STRW created a 'contained double rope system', on a single line of rope.  This contained double rope system travels with the climber as they move around the tree, allowing a consistent level of friction on the hitch, which is impossible to achieve in double rope climbing.