Built By Data: NFL Helmet Innovation
What Pros Wear: Top 5 Helmets Rated by the NFL & NFLPA - What Pros Wear
Guardian Cap Results: “Exceeded Our Expectations”
EXPLAINER: NFL using helmet caps for player safety, research
Complaints begin regarding Guardian Caps, despite one important hidden benefit - NBC Sports
The link between head injuries and CTE in football, explained - Vox
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
Helmet Innovation: More and Better Choices, Fewer Concussions
Report: More than 100 diagnosed concussions left out of NFL studies, including injuries to ex-Cowboys QB Troy Aikman