A plaquette (auto-blocking) device allows the belayer to use the device in an auto-locking “guide mode” by clipping it directly to an anchor, which is ideal for belaying multiple followers on a multi-pitch climb. It has a metal loop that enables this assisted-braking function, where a fall on the climber’s rope locks the brake strand. Examples of common plaquettes include the Petzl Reverso and Black Diamond ATC Guide.
It can be complicated to release a loaded plaquette. In this video, we show a few different techniques to lower someone on a loaded line.
Several AAI programs include instruction on the use of these kinds of devices. They include the following: