Features: This product is fully-functional, you can display the battery voltage, battery power, you can also-plug directly into the phone or other equipment-charging. 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. This product uses synchronous rectification step-down chip scheme, low heat, energy saving and environmental-protection. This product is-compact in structure, making full use of space and reducing-costs. Can be used as battery voltage meter, battery capacity tester and temperature indicator panel for car, marine, boats, etc. Specifications: Material:ABS Indicator Size:Approx.6.12x3.33x1.4cm/2.4x1.31x0.57inch Current: 50A 100A 300A 500A Note: .Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. .Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thanks for your understandings. Package includes: 1x Battery Capacity Indicator