Feature: 1, This product is fully functional, you can display the battery voltage, battery power, you can also plug directly into the phone or other 5V equipment charging. 2, This product is suitable for all kinds of outdoor power, mobile power, instrumentation and other equipment additional battery power voltage display and additional USB to charge the phone and other functions. 3, this product uses synchronous rectification step-down chip scheme, low heat, energy saving and environmental for protection. 4. This product is compact in structure, making full use of space and reducing costs. Product 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 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 power resolution: 10% 25% 40% 50% 60% 75% 90% 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 26 18mm Note: Item color displayed in photos may be showing slightly different on your computer monitor since monitors are not calibrated same. Please allow 1-3mm slight deviation due to manual measurement. Thank you! Package includes: 1 * Blue LED Digital Display Voltmeter