Guardian Caps leave some NFL players and coaches with concerns: 'You feel like a bobblehead'
Guardian Caps Guardian Sports
CFL introduces mandatory extra helmet protection for multiple positions. As well as other new health & safety measures. : r/sports
Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Caps', NFL's Most Recent Attempt At Preventing Head Injuries
EXPLAINER: NFL using helmet caps for player safety, research
Helmet improvement not perfect solution to concussions
NFL players wear Guardian Caps to reduce head trauma during training camp
PLA donates guardian helmet caps to Onekama football program