Combination quartz and tide clock movement which averages the Atlantic lunar tide cycle. The tide sector is calibrated for the east coast of the United States. Uses a AA battery. (Note: The clock will work for other tidal bodies of water but will need to be re-set more frequently.)
Quartz movement for convenience and accuracy. The AA battery can be easily replaced from the rear of the case. The hinged porthole-style case is solid brass with a lacquered antique finish.