For the user to charge and discharge can be automatic identification and direction of bidirectional current , do not need to change the direction od wiring . After power off memory function , power off on the number of AH , it is convenient for people to observe and measure .AH number and current reset function , do not affect the next measurement .Voltage , current , charging capacity AH , WH , time , power will show at the same time , also , shou the all clearly information. With the function of output and shut off ., it cab flexible to open or shut off the output (need to relay ).With over voltage , over current , over power , the litmited time , charge protection function , etc . It can calibrate online , give a convenience for customer to correct the error in time . LCD panel can be manually put out or less than 300 mA automatically screen out in a minute . Through the HALL current sensor detection , the current through thr wire round hole through thr sensor , both side direction current can be detected . It is safe and convenient for the users. Specification: Size: 79x43x52mm / 3.11x1.69x2.04inch Material: Plastic Package Includes: 1 Piece Voltmeter Ammeter Voltage Current KWh Watt Meter Note: Please allow 1-3mm measuring deviation due to manual measurement. Due to the different monitor and light effect,the actual color of the item might be slightly different from the color showed on the pictures.Thank you!