Cardboard 2x2 flips are the most widely used coin holders in the industry. Just insert a coin, fold over and staple. Our Southern Star brand holders--made with lighter (thinner) cardboard-- take up less room in storage boxes than the Cowen's brand. The inside of Southern Star 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 shrink wrapped bundles of 50 holders or cases of 5000 holders (100 shrink wrapped bundles).