Which of the following is not an example of a mechanical belay device?

The HMS Munter carabiner, while useful for belaying in conjunction with a Munter hitch, does not operate as a mechanical belay device on its own. Instead, it is primarily a connector that allows the belayer to create friction via a specific rope arrangement. Mechanical belay devices typically use a more complex design that incorporates features like movable parts or a mechanism that assists with rope management and descent control, distinguishing them from simple connectors like the Munter carabiner.

In contrast, the figure 8 descender, auto-locking carabiner, and multi-purpose belay device all qualify as mechanical belay devices due to their ability to manage the rope more effectively and provide controlled descent options. These devices rely on mechanical actions to facilitate safety, control, and ease of use during rescue and climbing operations, which is not a characteristic of the HMS Munter carabiner.