Automotive Authority LLC&reg; Digital Waterproof Tachometer + RPM Recall for 2/4 Strokes RC Boat Baja, Zenoah The digital Tach/Hour meters will keep track of engine RPMs and running time for all types of gasoline powered engines. Hour Meter Function Can Be Used For Service Intervals Maximum RPM Recall Function LCD digital display (5 Digit Display) Works with: /4 Stroke Engines, RC Toys, PWC, ATV, Motorcycles, Marine Engines, Chain Saws, Tractors, Lawnmowers, and gas powered tools