Oppama PET - Engine Tachometer is an instrument measuring a shaft or disk's rotation speed, as in a motor or other machine. The Engine Tachometer device usually displays the revolutions per minute (RPM) on a calibrated analogue dial, but digital displays are increasingly common. This Engine Tachometer, also known as the PET-1000R, is pulse-activated. It detects and counts electric pulses produced at the time of ignition of gasoline engines and processes the detected signal into rpm readings according to the type of engines being monitored. This unit is designed for use with 2-stroke single-cylinder and twin cylinder and 4-stroke twin-cylinder and four-cylinder engines. This unit cannot be used for direct ignition engines. When the antenna lead is used, be sure to keep it free from contact with metallic surfaces to avoid possible errors in rpm readings. Product Specifications Brand: Oppama Length: 120 mm Model: PET-1000R Product: Engine Tachometer Weight: 0.3 Kg Width: 62 mm