A semi automated belay device. To belay, feed the rope smoothly through the device. If the leader falls, the sudden pull makes the cam pivot, locking against the rope. For lowering, operate the handle to unjam the rope & control the running of the free end of the rope. The Gri Gri is not a substitute for vigilance on the part of the belayer, who must remain attentive to the climber at all times.