Lithium Battery Capacity Indicator Module Blue Display Power Level Tester Specifications: Type: 3.7V/2S/3S/4S/6S Display color: blue Housing color: black+green Size: 45*20mm Material: plastic, electronic components Package list: 1 x lithium battery capacity indicator module Features: ** Wide application: Includes nickel-metal hydride batteries, 18650 and polymer lithium battery packs, lead-acid storage, electric vehicle batteries and electric equipment. ** Easy to use: You just connect the positive and negative terminals of the display board to the positive and negative terminals of the battery under test. ** Digital color: Features outline red, display block blue. (When the battery is full ,it will be on entirely) ** Display electricity quantity: (Note: N represents battery quantity) 1. When battery voltage is over N*3.3V, it will illuminate 1 block electricity quantity. 2. When battery voltage is over N*3.5V,it will illuminate 2 blocks electricity quantity 3. When battery voltage is over N*3.7V,it will illuminate 3 blocks electricity quantity 4. When battery voltage is over N*3.9V,it will illuminate 4 blocks electricity quantity 5. When battery voltage is less than N*3.3V,4 blocks display will be off. It means battery is less than 3.3V,and you should charge the battery.