Collector Challenge Coin, 44 mm diameter, 3 mm thick, Shiny nickel finish, black and white enamel highlights, base metal bronze alloy, 3D design on front and rear, Die struck (not die cast).  Weight of one coin is 43 grams compared to a silver dollar at 23 grams.  This is a popular souvenir, excellent quality.  For history of the challenge coin read: http://en.wikipedia.org/wiki/Challenge_coin