The Subtraction Strip Board provides an excellent visual lesson in subtraction through the use of its numbered red and blue strips and unnumbered natural wood strips.  The set includes a board with a grid of eighteen columns and twelve rows which is used along with the strips to show the difference when one number is subtracted from another.  The board measures 40 x 30 cm (about 16" x 12"), and the set comes with a box and a lid for storing the strips.