【LED Voltage Display】This SAE adapter has a built-in voltmeter. Detect and display the voltage when power is on. It is also a very convenient way to tell you if the connection is successful. 【Powerful Capacity】The SAE to USB adapter is designed for use on any 9-24 volt battery, and is used to charge any Phones, GPS, Camera, digital cameras, or any Smartphone or device that may be charged via USB. 【Over-charge Protection】CE & ROHS certified, display the current detected by the intelligent circuitry while charging. Intelligent circuit design protects against excessive current, overheating, and overcharging. .