Why do war movies, such as Saving Private Ryan, Band of Brothers, Platoon etc., show American troops wearing their steel helmets with an open chin strap? - Quora
Chinstrap Fitting
Army Helmet With Chin Strap - It's My Party
EXFIL® Oxygen Mask Strap Kit | Team Wendy
3M™ X5-S4PTCS1 Standard 4 Point Chin Strap with buckle for SecureFit™ Safety Helmet | 3M United States