These are some left overs from a 1984 contract for the Airforce Boonie hat . They are made of the unique military cotton-poplin material that is both wind and water-resistant. As far as we know, this particular type of material is no longer being manufactured. When we discovered this jewel, we bought them all. Poplin is renowned for its strength and durability. It is highly regarded by collectors. Only one size left in stock Size 7 (small).