Usually a metal device which the belayer uses to control the rope. There are sever types of devices, all of which create friction against the rope; thereby allowing the belayer to catch a falling climber
A mechanical device used when belaying. Many types of belay device exist, including ATC, grigri, Reverso, Sticht plate, eight, tuber, and the Munter hitch. Some belay devices may also be used as descenders.