Page 210 - Buck Tilton - Outward Bound Ropes, Knots, and Hitches 2 ed.

The Munter hitch works as a climbing device for belaying

and rappelling and should be learned by all climbers. The
knot grips a carabiner when a load is applied, but the rope
runs through the carabiner when the load is off. It should be

used with one locking carabiner or two non-locking
carabiners with the gates reversed. Test the knot on safe

ground by pulling aggressively on the standing part before
trusting it to save a life! Werner Munter, a Swiss guide,

popularized this knot, leaving his name in the annals of
climbing.

Munter Hitch: Step 1