True to Size: Purchase your normal size to wear under other layers. 18.5 micron, superfine, pure 100% merino wool. Pure Merino Wool is naturally antibacterial, meaning there is no treatment necessary to retain its odor resistant quality even when used for several days in a row. Unlike other fabrics, Merino keeps you comfortable from extremely high temperatures down to the coldest digits as well. Merino Wool is also naturally UV absorbent to eliminate shine and fire resistant. Lightweight, jersey-knit fabric. Flat lock seams for next-to-skin comfort. Ergo cuff with thumb loops. Covered by First Lite’s Warranty. ASAT Finish