Metal Safe Corrosion Inhibitor " emits an odorless vapor that permeates coin holders. When Metal SAFE vapor contacts metal, it lays down an invisible barrier that protects, but does not coat, clean or change coins. The protective effect disappears once the coin is removed from the storage area. Metal SAFE works with all types of coinage metals, and all coin holders, even slabs. It works at any humidity level, so there is no need to use silica gel or other moisture absorbers."
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