This clock keeps accurate time using energy from a battery that you make. Simply add weird liquids such as soda, fruit juice, dilute ketch-up, salt water, etc. to the two containers, insert four metal electrodes, and connect with three wires. Approx. 15 cm (6 in.) wide.
Replacement zinc electrodes also available. Pack of 4. (Brass electrodes should not need to be replaced, only cleaned occasionally.)