Electronic Tachometer RPM Meter  Ignition Coil  Driven 85mm Parameter Value Range = 0-3000 RPM Input = Ignition Coil Tachometer Air Core based Voltage = 12V Operating voltage = 11-27V Size = 3 3/8"  / 85 mm (Dia) Front ring = Chrome  SAE Case, Bolt and Clamp Zinc Plated Dial(Base) =  Black Dial (Printing)  = White (when illuminated Red) Indicator Pointer = White , Illuminated Deflection angle = 240° Connection Type = Stud 5mm Calibration Dip Switch provided on back Connection  P= Positive terminal of the battery S= Signal from Ignition Coil N  = Negative terminal of battery PLEASE VERIFY THAT THIS IS THE CORRECT ONE YOU NEED  USED ON ALL TYPES OF EQUIPMENT, POWER UNITS, TRUCKS, ETC USED COMMONLY ON OLDER WOOD CHIPPERS. BANDIT, MORBARK, WOODCHUCK, ETC Brand New Electronic Tachometer which is suitable for Tractors, Trucks, Heavy Vehicles, Construction Equipment and Earth Moving Equipment, Diesel Generator And Marine Engines & Yachts.