The DT2240B Portable Digital Stroboscope Tachometer (Battery Not Included) highly recommended here adopts advanced microcomputer (CPU) technique， photoelectrical and anti-interference technology， all together contributing to making non-contact speed measurement realized. It also helps you a lot with detecting the state of moving object and surface defects. The large LCD screen with backlight is easy and clear to read. Featured with low power consumption and digital control， this stroboscope will be your regretless choice!                                    Features             Adopt advanced microcomputer (CPU) technique， photoelectrical and anti-interference technology<br> Large LCD display with backlight<br> Digital control to help adjust flash frequency<br> Low power consumption， safe and energy-saving<br> Designed to help detect the state of moving object and surface defects and bring non-contact speed measurement <br>                                                            Specifications             Model     DT2240B    <br> Color     Black    <br> Material     Plastic    <br> Display     5 Digits， LED with Backlight in It    <br> Accuracy     0.05%    <br> Measurement Range     60-40000RPM / FPM    <br> Power Loss     About 60mA    <br> Power Supply     4 x AA Batteries (Not Included)    <br> Voltage     1.5V    <br> Time Base     10MHz Quartz Crystal Oscillator    <br> Dimensions     (8.27 x 2.95 x 2.17)" / (21 x 7.5 x 5.5)cm (L x W x H)    <br> Weight     7.80oz / 221g     <br>                                                             Package Includes            1 x Digital Tachometer<br>1 x Chinese Manual<br>1 x English Manual<br>