SmartWool Men's Merino 150 Printed Boxer Brief FABRIC: 87% Merino Wool 13% Nylon Fully functional fly - 'Size M inseam: 6" (15 cm) Wide elastic waistband (40 mm) designed for ultimate comfort; keeps Merino next to skin Flatlock seam construction designed to eliminate chafing Smartwool's lightest weight Merino jersey fabric uses a nylon core to increase durability while keeping Merino Wool next to skin Fully functional fly Wide elastic waistband (40 mm) designed for ultimate comfort; keeps Merino next to skin Flatlock seam construction designed to eliminate chafing Size M inseam: 6" (15 cm) Machine Wash Warm, Gentle Cycle Wash With Similar Color Do Not Bleach Tumble Dry LOW Cool Iron When Needed Or Dry Clean - For best appearance, wash garment inside out and flat/line dry.