Level Two of the ECWCS (Extended Cold Weather Clothing System) Rothco's Mid-Weight Thermal Shirts are an essential base layer for military and tactical professionals. The highly breathable, moisture-wicking polyester and spandex material is designed to protect from the harshest elements. Rothco’s mid-weight underwear tops feature a zip up collar, long back tail, and thumbholes in the sleeves for maximum comfort and fit. The grid fleece fabric features anti-odor properties for long-lasting wear.