Georgetown Pottery Tide Clock - Ivory Wave The patented off center circle design tells the height and direction of the tide. Hand up is high tide and hand down is low. Runs on lunar time. Simply set to the body of water of your choice. Designed by a fisherman nearly 40 years ago. Makes a great gift for a fisherman, boater, beach goer or lover of the sea. Runs on lunar time, 24 hours 50 minutes Uses 1 AA battery (not included). Measures 7.5 inches in diameter Handmade in Maine