1-7/8" with glass cover over colorful embossed tin insert showing a pair of birds by their nest on a tree branch. Compartment contains 5 small white balls to place into the next as eggs. Underside has cardboard insert with advertising for a shoe firm in Cleveland, Ohio. However, a good bit of the text on the left-hand side has worn off and remaining surface has some browning but remaining letters are easily readable. Puzzle side is clean. Early 1900s.