... TACH&MOTION&SURFACE MAR. Product Name:DT2239B Handheld Stroboscope(60-19,999RPM)This tachometer is used the microcomputer (CPU) technique, photoelectrical ... with backlightDigital control adjust flash frequenceLow power consumptionMeasure range: 60~19,999RPMCoarse/Fine adjust amplitude:<1,000RPM Coarse adjust: ±10RPMFine adjust ...