Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Caps: Padded Football Helmet Cover – Guardian Sports
NFL mandates extra head protection for training camp
NFL report: concussions dropped 50 PERCENT when players wore new 'Guardian Caps' over the summer
Guardian Sports - Hustle Up 7 on 7
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
Padded helmet cover shows little protection for football players - Scope
Guardian cap' to prevent head injuries mandated for practices, CFL says
Funky-Looking Guardian Caps Rejected by NFL for Regulation Play, OK'd for Practice - Core77
Guardian cap' to prevent head injuries mandated for practices, CFL says
Guardian Sports - The Science Behind The Guardian Cap
Guardian Caps: Padded Football Helmet Cover – Guardian Sports
Puffy, spongy Guardian Caps could help curb NFL head injuries - The Washington Post