These Auto gage 8000 RPM 2-3/4in. Mini Tachometer and 1-1/2in. Mini Gauges are specificaly desinged for limited space installations. Auto gage instruments are engineered to monitor your engine with accuracy and tested to function with reliability. These compact instruments are easy to install. These tachs operate on 4, 6, or 8 cylinder engines with standard, electronic ignitions with 12 volts. Bezel Dia.=2-1/4in., Case Dia.=2-3/4in., Case depth =3-1/4in..