NFL turns to Guardian Innovations for protective helmet caps
Giants react to NFL's new 'Guardian Caps' at training camps - Big Blue View
Guardian Cap Use a Concern for Watt, Saleh Early in Training Camp - Sports Illustrated
NFL Mandated Guardian Caps: Controversial Change - Sports Illustrated Seattle Seahawks News, Analysis and More
First QB helmet designed to help reduce concussions approved by NFL, NFLPA
NFL Mandates Guardian Caps During Training Camp - Team Insight
What are Guardian Caps and how are they helping football teams?
EXPLAINER: NFL using helmet caps for player safety, research - The San Diego Union-Tribune
Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN