Seeking to reduce head contact, NFL mandates use of Guardian Cap helmet for early portion of training camp - ESPN
NFL training camps: Guardian Cap players are wearing over helmets, why
Complaints begin regarding Guardian Caps, despite one important hidden benefit - NBC Sports
Coverage of the NFL in Guardian Caps
Guardian Cap Debuts at Training Camps League-wide
What are Guardian Caps? NFL's latest padded helmets for added safety
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
The NFL is not doing enough to protect their players – The Dispatch
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
NFL players beginning to adopt protective Guardian Caps over helmets at practice - NBC Sports
Kirk Herbstreit gives his current college football playoff prediction