Brand New Tachometer with Digital Display Fits Echo 89780233331 99051130017 2 & 4 Stroke... Genuine Laser Part # 97978 This pocket-sized tachometer can be used wireless for quick readings or wired with supplied lead for hands free engine adjustments. Detects and counts electric pulses produced by the ignition of gasoline engines, it processes the detected signals into RPM readings based on the type of engines being monitored. Capable of monitoring RPM of 11 types of gasoline engines. Auto shutoff feature Can be used wireless or wired (connector supplied) Detachable tether strapMeasurable range: 100 to 19980 (RPM) Measurable engine: 2-Stroke 1 to 4 cylinder / 4-Stroke 1 to 8 cylinder Detection distance: 6” (150mm ) Accuracy: +/- 10r/min Battery life: Approx. 20,000 hours Dimensions: 4.72”L x 2.44”W x 0.511H Weight: 73g (DOES NOT WORK WITH GDI ENGINES) Genuine OEM Laser Part