. For any gasoline motor up to 2 cylinder. Displays RPM up to 9000. Allows hour monitoring for even the smallest outboard motors. Great for 2 or 4-stroke engines. Displays RPM when running total hours when off. No power or ground required. Water and shockproof. Automatically turns on and off with the engine. Includes 5' sensor wire. Sierra Part #56969P. No power or ground required Waterproof and shockproof design | Small Engine Tachometer/Hourmeter