The 4M Potato Clock teaches young minds the value of green energy in an illuminating way. The Potato Clock uses a pair of ordinary spuds to power a digital clock. This kit includes a digital clock, wires and prongs; two potatoes are all that's needed to create a working clock. This kit is ideal for young science enthusiasts, and offers a valuable lesson on the transformative power of green science. Detailed assembly instructions included. No batteries required. Potatoes not included.