The Subtraction Problems set includes wooden tiles measuring 4 x 2 cm with all of the possible subtraction problems using the numbers 1 through 20, as well as the answers on separate tiles measuring 2 x 2 cm.  The problems and answers are printed on the tiles in green, and the entire set comes in a divided wooden box with a colour-matched green lid with a subtraction symbol.  The box measures 16 x 11 cm.