Review on 🚗 85MM Waterproof RPM Tachometer Gauge for Car, Truck, Diesel Engine, and Marine Boat - LCD Digital Hour Meter, Red Backlight, 0-6000 RPM Range, 9-32V Compatible by Cory Jacobson

These tachometers fit easily in my boat's dashboard. Calibrating was easy enough despite poorly written/translated instructions. The arrows on the display clearly lag behind the engine speed. This is fine if you want an approximate figure for engine RPM, but don't rely on readings when targeting specific shift points when driving a manual transmission car. These are enough for now until I can spend the money on a better set.