Which component on a figure 8 descender stops the rope from sliding and forming a knot?

The ears of a figure 8 descender play a crucial role in stopping the rope from sliding and forming a knot. These ears create friction against the rope as it passes through the descender. When the rope is loaded with weight, such as from a user descending, the ears help to create the necessary resistance that prevents the rope from slipping uncontrollably. This friction is vital for maintaining control during a descent and preventing tangling or knot formation.

The body of the descender primarily serves as the main structure to facilitate the descent and does not contribute directly to stopping the rope. The locking mechanism, found on other types of descent devices, does not apply to the figure 8 descender, as it operates differently. The weight of the user does help maintain tension on the rope but does not directly prevent it from sliding nor does it address the potential for knots on its own. Thus, the ears are the key feature that provides the necessary friction for safe and controlled use of the figure 8 descender.