100% Cotton. Available S, M, L, XL To find the perfect fit first measure completely around your chest right under your arm pits. S = (34/36) M = (38/40) L = (42/44) XL = (46/48) Availability: Usually ships the next business day. MBS Monkey Crest T-Shirt monkeycrest$18.95S: MLXL Have a Question? Email us. Hours: Monday thru Friday 9 AM to 5 PM (EST) Closed Saturday and Sunday Web www.mountainboardshop.com