NFL players don Guardian Caps, designed to protect from concussion

#039;Guardian Cap' is the latest piece of equipment designed to mitigate repetitive head trauma. Not all players are on board.

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Pittsburgh Steelers helmets on the field at their NFL football

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NFL players don Guardian Caps, designed to protect from concussion

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Pittsburgh Steelers helmets on the field at their NFL football

Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN