100% polyester. The Jersey is a vintage replica of the original jersey worn by the RCAF Flyers - winners of the Olympic Hockey Gold Medal in 1948. The year 2023 marks the 75th anniversary of the gold medal win, and the RCAF Association is teaming up with the RCAF to commemorate this 75th anniversary as part of the RCAF centenary celebrations coming in 2024. Proceeds from the sale of this jersey help fund RCAF centenary events across Canada. Customers are responsible for size selection and for shipping costs in the event an item must be returned for wrong size selection. We are a non-profit organization.