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.
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
The Petzl Huits figure 8 square design reduces twisting of the rope and risk of girth hitch formation while rappeling.