1, This product is fully functional, you can display the battery voltage, battery , you can also plug directly into the phone or other 5V equipment charging. 2, This product is suitable for all kinds of outdoor , mobile , instrumentation and other equipment additional battery voltage display and additional USB to charge the phone and other functions. 3, this product uses synchronous rectification step- chip scheme, low heat, energy saving and environmental protection. 4. This product is compact in structure, making full of space and reducing costs. Colour: Black material: plastic Parameters 1, Static input current: 5-25mA, the lower the battery voltage, the smaller the current. 2, USB output: 5V/2A (a USB setting for recognition, a setting for Android recognition) 3, USB efficiency is up to 96% (because of the synchronous rectification circuit, the conversion efficiency is high and the heat is low. 4, 8 segment resolution: 10% 25% 40% 50% 60% 75% 90% 100% 5, The accuracy of the voltmeter is about 2% 6, Working temperature: -10 ~ +65 C 7, Working humidity: 10~80% (no condensation) 8, Opening size: 45 x 26 x 18mm Package included: 1 X Digital Voltmeter Battery Panel Meter with USB output Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.