The potato, salt water and mud. Be amazed at how they light up a bulb or a sound buzzer. Includes experiment guide for making a coin battery, a fork battery, a potato buzz wire game, and more. Caution: High voltage inspiration! Contains 4 zinc plates, 4 copper plates, 4 connection wires, 2 plastic cups, 1 paper cup, 3 screw caps, 1 light tower with led lamp, 1 sound chip with connection wire, 1 LCD watch movement with protective cover and 1 transparent adhesive tapes.