Guardian Caps: The new helmets worn by several NFL teams
NFL players wear Guardian Caps to reduce head trauma during training camp
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated
Truth About Guardian Caps
NFL introduces Guardian Caps across league to limit number of brain injuries in preseason
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
NFL players don Guardian Caps, designed to protect from concussion
NFL hopes to reduce head injuries with helmet experiment
In fall camp, Montana State using Guardian Caps for safety, preservation of game
Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries