This is a breathable hands free mouth mount, you put it on your mouth and bite down on the mouth piece, you then can record videos from a good height (not to high, and not to low of an angle).
Your head acts as a natural stabilizer, so you will get a more stabilized video.
It hangs the gopro just below your chin on your neck, and it is easy to move around with.
Its good for recording Surf, Long-board, Parkour, etc. type of videos.
it is very strong and wont break easily, so be careful not to break your teeth.

In the pictures, mine is longer because I'm taller and I wanted a lower camera angle, but it just gets in the way when I look down, so this model is shorter so it works well.