WEEMS & PLATH Nautilus Collection Waterproof Quartz Clock Precision quartz movement: accurate to +\- 15 seconds a month Displays both 24 hour and 12 hour clock Waterproof to a depth of 100 feet Low glare, satin black case constructed of solid aluminum, color anodized and sealed so that the finish will not peel, bubble or tarnish in extreme heat or cold. Glass crystal sits in a double O-ring seat for vibration, impact and thermal expansion protection Anodized dial is laser engraved Durable moveable red markers are made of U.V. stabilized polycarbonate and located outside the crystal for marking time or pressure All fasteners are stainless steel Case removes from bulkhead by turning 1/8 turn which allows for easy calibration, storage and anti-theft purpo Complete instructions, AA battery, and mounting hardware included Lifetime warranty