Built in protection turns off USB charging and prevents your parked vehicle's LFP (LiFePO4) or AGM (Pb) battery from draining - starts back up when vehicle fires up Creates weatherproof seal against inserted USB cable, or rideproof' cap seals when not in use - worry free phone, camera or GPS charging in any weather The portable and compact SAE to USB 2400mA charger for safe and fast charging of any USB device, including your phone, camera and GPS Connects to battery lead with industry standard SAE 2 pin connector - seals perfectly when mated with OpitMate SAE Monitors and displays parked vehicle's battery status - indicates battery is 'start ready' at the blink of an LED. CHARGER USB 2400MA