These large 9" buttons were used by clock makers in the early 1970s. Center has 5/16" hole where minute and hour hands attached to a reverse compartment that held the batteries. This is the face only with plain black cardboard reverse. Side edge at 10 o'clock has shallow dent about .5" long. Outer edges a bit "frosty" where there is air under the cello covering as made. Lower front reads "Lendan/Made In U.S.A." N. Mint.