Royal Mariner Time and Tide Porthole Clock - ChromeCHROME TIDE and TIME CLOCK #C622TC Quality quartz movement with dual functions: A conventional 12 hour time clock, with hours, minutes and seconds A tide clock with a period of 12 hours 25 minutes Hinged and latched front panel allows very easy battery replacement Flange base with drilled and countersunk holes for easy mounting to your bulkhead or wall Beveled glass front completes this traditional design GENERAL SPECIFICATIONS Base Diameters 116mm