NFL players wear Guardian Caps to reduce head trauma during training camp
NFL CMO Dr. Allen Sills explains importance of mandated guardian caps during training camp
Guardian Caps Guardian Sports
First QB helmet designed to help reduce concussions approved by NFL, NFLPA
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Caps are the latest effort to address CTE, football concussion concerns
NFL introduces Guardian Caps across league to limit number of brain injuries in preseason
Players, coaches react to mandatory use of Guardian Caps