Guardian Cap Results: “Exceeded Our Expectations”
Guardian Caps: NFL requires use of helmet cover at training camps
Could Guardian Caps be used during NFL games for player safety
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play
NFL exec suggests Guardian Caps worn to protect players during
NFL executive hints that Guardian Caps could eventually be worn in
Guardian Caps - Are the soft-shelled football helmet covers
NFL training camps: Guardian Cap players are wearing over helmets, why
American football - Wikipedia
Guardian Caps NFL: What player positions are required to wear them
Guardian Caps leave some NFL players and coaches with concerns