NFL announces more steps to reduce head injuries
NFL hopes to reduce head injuries with helmet experiment
What are Guardian Caps? Shadow Hills football using new device to reduce head injuries
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated
The impact of 'Guardian Caps' on player safety
Guardian Caps: NFL requires use of helmet cover at training camps to reduce head injuries
Guardian cap' to prevent head injuries mandated for practices, CFL says
NFL introduces Guardian Caps across league to limit number of brain injuries in preseason
Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Caps', NFL's Most Recent Attempt At Preventing Head Injuries