The Smartwool Merino 250 Patterned Men's Long Underwear Top is made from 100% Merino wool fabric with an interlock knit, which makes for enhanced comfort, breathability, thermoregulation and odor resistance. Shoulder panels eliminate top shoulder seams for a better fit, while the flatlock seam construction is designed to stop chafing. With the next to skin Merino, it wicks and regulates core temperature which makes it a go to layering option no matter the conditions you face during the cold weather months. Slim Fit, 100% Merino Wool, 10in Center Front Zipper, Shoulder Panels, Flatlock Seam Construction, Merino 250, Garment Weight: 285 g, 100% Merino Wool, Fit: Loose, Warranty: Lifetime, Material: Wool, Weight: Light, Type: Top, Wicking Properties: Yes, Recommended Use: Snow, Anti Odor: Yes, Moisture Wicking: Yes, Model Year: 2020, Product ID: 575263, Model Number: SW0NP601B99-M, GTIN: 0192361515740