Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Caps leave some NFL players and coaches with concerns: 'You feel like a bobblehead'
New NFL Equipment Has Player Safety As Number One Priority – NFL Alumni
NFL Health and Safety Fact Sheet
NFL players experiment with 'Guardian Caps' to protect heads
Do Padded Helmet Covers Actually Protect Football Players? - The Good Men Project
What are Guardian Caps? NFL's latest padded helmets for added safety
NFL players experiment with 'Guardian Caps' to protect heads
As NFL mandates Guardian caps in practice, area high school football teams have been using them for years, Sports
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Puffy Guardian Caps Could Reduce NFL Player Concussions
NFL hopes to reduce head injuries with helmet experiment
Guardian Caps Guardian Sports