The neck brace keeps your head straight and this in any crash is insanely important. When you crash and roll around, your body tends to move in ways it's not supposed, many times due to the conditions on Downhill, Freeride, Dirt Jumping or Slopestyle the neck moves the way it's not supposed to and this is when injuries happen. Totally preventive.
The neck brace limits some movement of the neck, so lessens your range of view. You definitely get used to it.
This is a great neck brace, considering the price for it and the way it handles it's job, it's a great buy! It does take time to get used to, but the way it prevents injuries from your upper body is great. As your neck remains still while your rolling after a crash, your upper body basically stays put and it suffers a lot less! It's a great BUY!