Guardian Caps: NFL requires use of helmet cover at training camps
NFL report: concussions dropped 50 PERCENT when players wore new
Coverage of the NFL in Guardian Caps
Guardian Caps - Are the soft-shelled football helmet covers
NFL concussion data could lead to broader use of Guardian Caps
NFL says Guardian Caps reduced concussions by over 50
Thoughts on Guardian Caps for Concussion Prevention - Smith
Coverage of the NFL in Guardian Caps