The distributors also purport that the coins have been struck using silver recovered from a vault in the rubble of the World Trade Center. The validity of this claim has not been confirmed. Distributors warn that the minting of the coin will cease once the quantity of recovered silver has been exhausted, and have therefore placed a limit on the number of coins that can be ordered per person. The coins are not solid silver, but are silver clad (0.0001 inch (2.5 micrometre) layer). Actual silver content is 45 mg, or 0.00145 troy oz.