Cardboard 2x2 flips are the most widely used coin holders in the industry. Just insert a coin, fold over and staple. Cowen's brand holders--made with heavier (thicker) cardboard-- provide more protection for your coins than the other brands of 2x2 cardboard coin holders available on the market. The inside of Cowen's holders are lined with DuPont Mylar, the chemically most non-reactive lining available for coins. Mylar does not tear or scratch and is also the most moisture resistant film available. Mylar film is also dustproof with the lowest available permeability. Sold in bundles of 100 or cases of 3000 (30 bundles).