What is a HMS carabiner? If you don’t speak German, it’s a reasonable question.

It’s actually an acronym for “Halbmastwurf sicherung”, which kind of translates to “Munter hitch belay carabiner.” 

In American climber slang, the HMS biner gets shortened to a “pearabiner”, which is certainly easier to remember when looking at it's shape. So basically it is a large, locking pear-shaped carabiner, suitable for belaying with a Munter hitch.

Why use the HMS?

What are the advantages? For one, using a pearabiner like this offers a wide, quiet flat bottom edge, making it easy to belay off of this with a Munter hitch. The wide gap in the bottom allows the knot to flip back and forth as you take in or let out rope.

Furthermore, this wide, flat surface allows you to clip other carabiners onto it and be able to add or remove them easily, even if one carabiner is loaded. If you were to use a different carabner like an asymmetric or  “D” shaped one on your master point, the loaded carabiner will often slide/pinch down on the other ones, making removal very difficult.