Guardian Caps: Why some NFL players are wearing them in training camps
Guardian Caps', NFL's Most Recent Attempt At Preventing Head Injuries
Guardian Caps, a soft-shell helmet cover, among CFL's new player-safety initiatives
Xaverian High in Mass. introduces Guardian Caps for football players
Padded helmet cover shows little protection for football players - Scope
EliteTek Soft Padded Helmet Headgear Protection: 7on7 Tournaments, Flag Football, Team Sports, Training, Rugby, LaCrosse, Soccer, Practice & Epile
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
NFL training camps: Guardian Cap players are wearing over helmets, why
Bellmore-Merrick athletics debuts new guardian caps, Herald Community Newspapers
Guardian Cap used by football teams to protect against head injury – The Denver Post