Weems & Plath Endurance Chrome & Black Pearl Instruments Barometer . Weatherproof instruments that won t tarnish or corrode!Ultra-hard mirror finish stands up to tough outdoor conditions, and is guaranteed never to corrode. Endurance instruments will always look like new, even after long-term exposure to the elements. They never need polishing or refinishing. The weatherproof clock and barometer feature a silicone O-ring seated behind the beveled glass crystal for protection from water intrusion. Not only do these instruments hold up to harsh weather, they also feature a Slide n Lock Mounting System that lets you lock in, or remove, each instrument easily from its special mounting plate to make adjustments or store it. Now, you won t have to unscrew it from the bulkhead every time you need to replace the batteries. Case Material: Brass Movement Type: Quartz clock (AA battery included) Bezel: Fixed Dial Diameter: 4 7/8″ Case Diameter: 6″ Case Depth: 1 5/8″ Case Drilled For Mounting: Yes