Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
NFL hopes to reduce head injuries with helmet experiment – The Morning Call
Arizona Cardinals' J.J. Watt critical of Guardian Cap: 'Feel like a bobblehead' - ESPN
Guardian Cap debuts during minicamps in effort to reduce avoidable head contact
Guardian Cap - Soft-Shell Protective Helmet Cover : Football Helmets : Sports & Outdoors
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
What's With Those Padded Caps NFL Players Are Wearing In Training Camp?
Guardian Cap - Soft-Shell Protective Helmet Cover : Football Helmets : Sports & Outdoors
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post
Why High School Football Coaches use Guardian Caps - Footballscoop
NFL says positions wearing Guardian Caps saw 52% decrease in concussions - NBC Sports
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated
NFL fans react to new guardian cap rules
NFL hopes to reduce head injuries with helmet experiment