These USMC FROG Silkweight Long Johns combine the comfort of a lightweight base layer with extra resistance to fire and heat. Originally seen issued to marines during military engagements in Afghanistan and Iraq. Dependable spring/fall thermal management which excels particularly under high activity. Silkweight base layer Long Johns 78/22 modacrylic/flame-resistant rayon Quick-drying and moisture-wicking Antimicrobial for long-lasting freshness