Fangrui Product Details Applicable Battery: Supports: 1. 3-20 Series Lithium Battery Pack, 2. 4-24 Series Lithium-iron Battery Pack, 3. Lead-acid Battery Of 12v, 24v, 36v, 48v, 60v, 72v, 84v. This Product Also Supports Custom Mode In Range Of 9.5-100v. Display: The Product Uses Digital Display Lcd With Backlight, Equipped With A Strengthened Waterproof Screen, It Displays Both Battery Voltage And Remain Capacity Simultaneously, Enable Users To View The State Of Battery Clearly. Power-off Memory: After Cutting Off The Power Supply Of The Voltmeter, The Function Setting Keep The State Before Power-off. Low Voltage Alarm: The Low Voltage Alarm Work When Battery Power Is Less Than (battery Flash). This Reminds You That The Battery Needs To Be . Low Power Consumption: The Voltmeter Has A Very Low Power Rate, At Normal Mode, Its Self-current Consumption Is Below 15ma, While Low-power-consumption Working Mode Is Below 1ma. Calibration: A Calibration Screw Hole Allows To Adjust The Voltmeter To Zero Bias By Simply Twisting The Scr