The former Harry W. Bass Jr Research Foundation example. Photo courtesy of David Cassel. Examples are known in the following compositions: Nickel J644/P716. About half a dozen are known. Copper J645/P717 Only 3 are known. Aluminum J646/P718 About a half dozen are known. The listing of this in silver J643/P715 has been discredited by the research of David Cassel. David Cassel's book on Postage Currency Patterns is now available. For more on this, click here.