Leuchtturm Matrix 20mm Self-Adhesive Coin Holders, reference 313727, pack of 100 units, are a set of self-adhesive holders for archiving coins. Leuchtturm is a German brand founded in 1917 in Hamburg, considered a world leader in collection systems for philately and numismatics, with a catalog of over 6000 items covering more than 140 collection areas. Made of sturdy cardboard with a transparent film window free of plasticizers and acids, measuring 50x50mm externally. Simply place the coin in the center and press the two self-adhesive halves together to permanently seal, protecting the coin from scratches, oxidation, and direct contact with fingers. This 20mm reference is suitable for small to medium diameter coins, one of the most common sizes for coins in circulation.