The Petzl Gemini Double is a lightweight, compact, high efficiency Prusik minding pulley - ideal for progress capture 'fiddle blocks' in rigging and rescue systems where mechanical advanatge is required. Two Petzl Gemini Doubles combined with a length of appropriate cord and a simple Prusik will make your hauling and rigging tasks much easier. The pulley sheaves run on sealed bearings for excellent efficiency (91%). A powerful, lightweight tool for multiple configurations.