DRIFIRE Flame Resistant Military Lightweight Long Sleeve Shirt Fabric DF2-446LS 5.4 oz. lightweight soft fabric that prevents chafing Approved for Aviation and Armored Crew Member use Patented drirelease advanced wicking technology with ribbed collar to maintain shape. Made in the USA ASTM F1506, NFPA 70, CAT1, 4.5 cal/cm2