NFL players experiment with 'Guardian Caps' to protect heads
NFL players wear Guardian Caps to reduce head trauma during
Seeking to reduce head contact, NFL mandates use of Guardian Cap
Why are NFL players wearing padding on helmets at training camp?
Players, coaches react to mandatory use of Guardian Caps
NFL's use of Guardian padded helmet caps in camp draws support and
Eagles players on Guardian Caps: 'We look a little goofy,' but all
Large Bubble Helmets Are Guardian Caps, NFL's New Safety Measure
NFL's use of Guardian padded helmet caps in camp draws support and
Get A Load Of These Big Dumb Helmet Helmets