Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
Guardian Caps Guardian Sports
Guardian Cap used by football teams to protect against head injury – The Denver Post
EXPLAINER: NFL using helmet caps for player safety, research
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
What is a Guardian Cap? Meet the NFL's newest safety measure
Guardian Caps: Why some NFL players are wearing them in training camps
NFL CMO Dr. Sills on Guardian Caps Mandate >> Guardian Sports
Guardian Caps Guardian Sports