Mercury – Water Pressure Gauge 0–30 PSI | Cooling System Monitoring | Black Face | Black Bezel | 79-8M6020031Mercury Water Pressure Gauge 030 PSI Cooling System Monitoring Black Face Black Bezel 79 8M6020031 OverviewThis 030 PSI water pressure gauge gives you a clear look at how well the cooling system is moving water through the engine. Out on the water, the needle settles into a smooth, steady sweep, so you can spot changes without squinting or guessing. It reacts naturally when you trim up, get on plane, or run through chop. Its one of those gauges that