The self-locking capability of the Black Diamond ATC Guide belay device makes it an excellent choice when you cast off on multi-pitch traditional, ice, and alpine climbs. The ATC Guide belays a leader just like any other tube-style device, but it can also be connected directly to your anchor to create a self-locking system when you're belaying one or two following climbers. Its unique release point lets you lower a following climber when the ATC Guide is in self-locking mode, even if he is a lot heavier than you. The aggressive V-notch allows this belay device to work on ropes from 7.7 to 11mm.