Guardian Caps - Are the soft-shelled football helmet covers effective at limiting head injuries? - ESPN
Guardian cap' to prevent head injuries mandated for practices, CFL says
Complaints begin regarding Guardian Caps, despite one important hidden benefit - NBC Sports
Football Guardian Cap draws mixed reviews from players, experts for safety effectiveness - The Daily Tar Heel
NFL CMO Dr. Allen Sills explains importance of mandated guardian caps during training camp
NFL's use of Guardian padded helmet caps in camp draws support and skepticism - The Athletic
Guardian Cap Results: “Exceeded Our Expectations”
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated
NFL mandates use of Guardian Caps for training camp in 2022 - Cincy Jungle