Broad CompatibilityNot only fits for DC 12-24V automobile but also have a perfect performance on boat, marine, motorcycle, 4-wheels, RV etc.MultiProtect Safety SystemCertified by RoHS, CE, and FCC. The surge protection, overvoltage protection and more advanced safety features keep all your devices safe.Real Time Monitor VoltageMonitors the vehicle's battery and electrical system automatically in real-time and indicates the voltage in the screenHow to install?1. Drill a hole with about 1.13inches, diameter by a hole opener.2. Put the USB charger into the hole.3. Screw it tighty.How to connect?The terminal on the back are labeled with " " and "-" for positive and negative poles.Package Included:2x 23.7 Inches Wire with 10A fuse2x Dual USB Charger Socket