NFL players wear Guardian Caps to reduce head trauma during training camp
Shell game: Player safety looming concern as new season approaches, Local Sports
NFL players beginning to adopt protective Guardian Caps over helmets at practice - NBC Sports
NFL players don Guardian Caps, designed to protect from concussion
Guardian Cap - Soft-Shell Protective Helmet Cover : Football Helmets : Sports & Outdoors
NFL CMO Dr. Sills on Guardian Caps Mandate >> Guardian Sports
NFL reports reduction in concussions among players who wore Guardian Caps in preseason - The Athletic
Guardian helmet caps are taking over football practices across America
Players, coaches react to mandatory use of Guardian Caps