Professional Timing Light SP62042Tachometer: 249 to 9,990 RPM (+ 1% Accuracy). Advance Degrees (2 and 4 cycle DIS and Conventional): 0 to 90 (+ 5 Accutacy). Dwell: 0 to 180 2 12 cylinders (+ 1% Accuracy). Voltage: 10 to 16 volts DC (+ 1% Accuracy). Rotating Barrel For better aim at timing mark and LCD viewing angle. Optically Correct Lens. Rotating barrel for better aim at Timing mark & LCD Viewing Angle