Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Caps added to help reduce football concussions - The Witmarsum
NFL Players Experiment With 'Guardian Caps' to Protect Heads – NBC Connecticut
What Pros Wear: Guardian Caps What are Those Helmet Covers Being Worn in Practice? - What Pros Wear
MTSU reduces concussion risk with padded helmet covers
Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian Sports - The Science Behind The Guardian Cap
High school football looks to Guardian Cap for head safety
Guardian Cap - Soft-Shell Protective Helmet Cover – Mario Luna Football
Guardian Cap - Soft-Shell Protective Helmet Cover – Mario Luna Football
Guardian Caps Guardian Sports
Guardian Caps: Why some NFL players are wearing them in training camps