Truth About Guardian Caps
High school football teams go soft in the fight against brain injuries
Why the Ticats are wearing those giant helmets at practice
NFL hopes to reduce head injuries with helmet experiment
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Steelers debut new, safer helmets for off-season training
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
Guardian Caps, a soft-shell helmet cover, among CFL's new player-safety initiatives
Padded helmet cover shows little protection for football players