NFL mandates use of Guardian Caps for training camp in 2022 - Cincy Jungle
NFL hopes to reduce head injuries with helmet experiment
NFL 2023 Season Guardian Caps Mandate Supported By 52% Concussion Drop – Sports Techie
NFL expands rule against misuse of helmet; Guardian Caps required in regular season, postseason
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
NFL CMO Dr. Allen Sills explains importance of mandated guardian caps during training camp
Why are NFL players wearing padding on helmets at training camp?
Guardian Caps Guardian Sports
EXPLAINER: NFL using helmet caps for player safety, research