Can new technology help cut down on concussions? (video)
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
Guardian Caps Guardian Sports
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Caps Guardian Sports
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
Guardian Caps Guardian Sports
NFL executive hints that Guardian Caps could eventually be worn in games, along with position-specific helmets