At Stanford, David Camarillo chases the dream of a helmet that can prevent brain disease related to playing football. It’s filled with water. Really. Brain experts say he’s wasting his time.

The helmet, developed by AT&T and Gallaudet University, will debut at the school's Saturday game. When a coach chooses a play on a tablet, it will then display on a small lens on the player's helmet.

A new helmet, designed specifically to offer greater protection when a quarterback's head hits the ground, will be available for the first time to NFL players this season.

The following prohibited helmet models perform poorly in laboratory testing, have been discontinued by the manufacturer, or were produced by companies no longer manufacturing football helmets.