The Singing Tree Rope Runner is a single rope ascent and descent device for 11-13mm 24-strand ropes. The Rope Runner provides smooth control of the rate of descent for the climber on single, 24-strand line. It has become one of the most popular devices for SRT climbing. The tested and recommended rope for the Rope Runner is the 11.5 MM 24 strand Rocket Line, Blue Craze, Sunburst or Cherry Bomb from All Gear.