Dual USB Charger and Socket Blue Panel Mount Sea Marine 12 Volt Motorcycle Boat Rv Truck Plug Power Outlet #Ycn8/cr/cykd/tplt/4sq 2 Port USB Socket Charger A great quality USB charger very reliable range of 12v power sockets/outlets Comes with dust cover Heavy duty construction DC Voltmeter:A high quality voltmeter for checking the state of your battery and battery charger. Can indicate a poor or bad charging system. Tells whether your battery is holding a charge or not.