SCTROBOSCOPE The model DT-2239A is a microprocessor circuit design, high accuracy, digital readout, light duty STROBOSCOPE/ TACHOMETER that is ideal for inspecting and measuring the speed of moving gears, fans, centrifuges, pumps, motors and other equipment used in general industrial maintenance, production, quality control, laboratories and as well as for schools and colleges for demonstrating strobe action. Specification:  Display 0.3 " LED, 4 digits. Stroboscopic Flash Rate: 100 to 10, 000 flashes per minute ( FPM)  Acc. : 100 - 5, 000 FPM/ RPM ) = ± 1 digit. > 5000 FPM/ RPM = ± 0.05%  Res. : 10, 000 FPM/ RPM = 1 FPM/ RPM, > 10, 000 FPM/ RPM = 10 FPM/ RPM Power Supply 110 Vac 10% , 50/ 60 Hz. Power current : Less than 30 Watt. Dimension HWD - 21 x 12 x 12 cm( 8.3x4.8x4.8 inch) . Weight 1Kg/ 2.2 LB.