The RC-3100 Pre-Tension pulley has been designed to work in conjunction with the range of RC Lowering Devices. Simply attach a prusik to the main rigging line attach the pulley to the prusik place a couple of wraps around the lowering device then loop up to the pulley; you now have a simple 3:1 ratio tensioning system which can easily be loaded, tensioned, and removed single handed. Work Load limit: 150Kg Maximum Rope Size: 19mm Weight: 650g Pulley Diameter: 94mm Length: 157mm Width: 105mm Depth: 62mm Manufature: ISC