Why are NFL players wearing padding on helmets at training camp?

Bengals linemen, linebackers and tight ends wore Guardian Caps at training camp after the NFL required the padding for some position players this preseason.

NFL hopes to reduce head injuries with helmet experiment

Why are NFL players wearing padding on helmets at training camp

Cowboys seen wearing protective, NFL mandated Guardian Caps at

Why are NFL players wearing padding on helmets at training camp?

NFL players beginning to adopt protective Guardian Caps over helmets at practice - NBC Sports

Why are NFL players wearing padding on helmets at training camp

NFL Makes Ruling On Players Wearing Guardian Cap During Game - The Spun: What's Trending In The Sports World Today

What are those caps football players are wearing?

NFL Players Seen Sporting Futuristic New Helmets During Training Camp (PICS)

Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post

NFL training camps: Guardian Cap players are wearing over helmets, why