What device combines a pulley, belay, and descender into one system?

The CMC Multi-Purpose Device (MPD) is specifically designed to serve multiple functions in rescue scenarios, combining the capabilities of a pulley, a belay system, and a descender into a single, versatile tool. This multifunctionality allows rescuers to efficiently manage rope operations, whether they are lowering or raising a victim or team member, or performing a belay during a descent or ascent.

With the MPD, users benefit from its compact design, which simplifies equipment needs and reduces the complexity involved in managing separate devices. Its design supports various techniques, enhancing the overall safety and effectiveness of confined space rescue operations, where quick and reliable gear changes are crucial.

In contrast, the other options, while useful in rescue operations, do not offer the same multifunctional capabilities. The eyelet pulley, for example, is primarily a component to redirect force in a rope system. The rescue ascender is designed to facilitate ascent and does not have the belay or descending functions. A mechanical advantage device is typically used to assist in lifting heavy loads but does not inherently include belaying or descending capabilities. Thus, the MPD stands out as the comprehensive tool that integrates these critical functions for a confined space rescue.