The Revolver Keylock Carabiner by DMM. The Revolver is now well established as part of a comprehensive Trad leading rack. It is a unique piece of kit which offers very real benefits to the climber. So what does it do? In simple terms the carabiner uses rolling friction rather than the sliding friction of the rope over the bar typified by a standard carabiner. In this case the rope rolls over the pulley wheel which means much less friction is created. Less friction means less force holding the climber back, which makes upward progress a lot easier.
However, there are other important factors to consider too. Since the rope rolls over the roller, there will be less wear and tear on your rope which will increase its working life considerably. Also, by reducing the friction the forces involved when a climber falls are more evenly distributed throughout the system, resulting in less force being inflicted on the last piece of protection placed. If this last piece is marginal, it could be a very real benefit.
Please note that the Revolver is not recommended for frequent use lowering situations. In these instances you should choose a suitable Pulley or Connector which can handle the wear.