Petzl GRIGRIDescription Belay device with cam assisted blocking, designed for the gym and crag: feeding slack and catching falls are accomplished using standard belay techniques, always keeping a hand on the brake side of the rope easier belaying, thanks to its cam assisted blocking: when the climber falls or is at rest, the rope tightens, making the cam pivot to pinch and block the rope cam assisted blocking offers leeway for the brake side hand position,