This box actively protects your collection from oxidation and ageing thanks to the INTERCEPT� material inside. Suited to protecting coins, medals and paper. Suitable for coin sets, postcards, letters, stockcards, documents etc., up to 180 x 160 mm The way an INTERCEPT� box works is based on over 30 years of patented INTERCEPT� technology: the copper particles contained in the material permanently bond with corrosive gases and create a neutralised atmosphere in the shortest time possible, protecting the coins and documents from tarnishing (Guaranteed protection up to 15 years*!). This method has been proven in line with approved DIN, EN, ISO and ASTM standards. In order to prolong the effectiveness of the INTERCEPT� box beyond 15 years, it is recommended that you close the box immediately after use and avoid opening it frequently.