Like the munter hitch, the monster munter can be used as a friction device for controlling descent. It can be used to rappel or to lower someone else. The monster munter generates considerably more friction than the munter hitch, making it ideal for lowering large loads, like 2 people, or for slippery, small-diameter ropes.
The monster munter doesn't twist the rope as bad as the munter hitch. It requires a minimal amount of gear - just a locking carabiner.
Like the regular munter, the monster munter imposes a lot of wear on your rope. The sheath will get fuzzy if you rappel with the monster munter too much.