NSF Slim Work Shirt in Grey. Size S, M, L. 100% cotton. Made in USA. Machine wash. Front button closure. Chest patch pocket. Buttoned cuffs. Flannel fabric. NSF-MS159. 6314-MFP. Based out of California, NSF has caught the eye of many. With their clean design and boyish charm, NSF is recognized for its relaxed, modern style looks.