This state-of-the-art collection is waterproof and functions extremely well in the punishing saltwater environment. The low glare, satin black case of each precision instrument is constructed of solid aluminum that is color anodized and sealed so that the finish will not peel, bubble, or tarnish. The glass crystal sits in a double O-ring seat for vibration, impact, and thermal expansion protection. The anodized aluminum dial is laser engraved. The durable moveable markers are made of U.V. stabilized polycarbonate outside the crystal for marking time or pressure. All fasteners are stainless steel. Both the clock and barometer can be purchased with or without the optional incorporated fluid dampened inclinometer. To calibrate the movement in either the clock or barometer, twist the case 1/8 turn to remove the case and leave the back plate on the bulkhead. This feature is also convenient should you want to remove your instruments for storage or anti-theft reasons.