PETZL - Twin, High Strength, Very High Efficiency Double Prusik Pulley INTENDED USE: Special side plates designed for use with a Prusik friction hitch in progress capture systems. VERSATILE: Parallel mounted sheaves and auxiliary attachment point for creating different types of hauling systems, including the most complex. EFFICIENT: Large diameter sheaves mounted on sealed ball bearings for excellent efficiency. MULTIUSE: Accepts up to three carabiners to facilitate use. WEIGHT: The TWIN weighs 450 grams.