Here's what other sites are saying:
The Petzl Huit is a figure-eight descender for descending on single or double rope.
The Petzl Huit is a figure-8 descender for use on a single or doubled rope.
The Petzl Huits figure 8 square design reduces twisting of the rope and risk of girth hitch formation while rappeling.
Petzl Huit Descender FEATURES of the Petzl Huit Descender Square shape to reduce kinking the ropes and formation of a lark's head knot Compact and lightweight