This special bank can hold as many as 50 quarters or other coins, but always appears completely empty! Drop a coin into the top and it disappears! Great for teaching about mirrors or for experimentation with a diode laser. Simply aim the laser into the front of the bank to reveal a clue to its secret.Only those who know its secret can open the bank. Secret opening instruction included. Styles may vary slightly. (~3.5 x 3.5 x 3.5 inches)