The ˜Air Traffic Controller aka the ATC was created by Black Diamond back in 1993 ushering in a new age of belaying. Since then, the ATC has gone through multiple iterations and is now a time-tested and versatile tubular belay device that provides ample friction for belaying. The ATC-XP features multiple friction modes to handle nearly any situation, plus machined windows through the device shave weight, and the versatile design accepts ropes from 7.7 to 11mm.