The Men’s Versa Crew Neck Long Sleeve Fitted Base Layer is a performance shirt designed to keep you comfortable on the job – without slowing you down. The Regulator? fabric used to make this garment keeps you warm in cool weather while also allowing for exceptional breathability in hot weather. With an arc-rating of 4.9 cal/cm2, CAT 1 and NFPA 2112 – this Tyndale product is proudly manufactured in the US. Regulator is a registered trademark of iFR Fabrics.