Car data saver cable for OBDII port connection1、Red clip link back-up battery positive, negative black negative. Prevents electronic memory loss when disconnecting a vehicle\u0027s battery preserves vehicle codes and electronic presets. 2、You can use this car data saver to keep your car\u0027s computer powered through the OBDII port or the cigarette lighter socket on the car while you replace the car\u0027s storage battery. The car data saver needs an additional 12V storage battery as a temporary power source. It is a very useful tool for car service. 3、The emergency power interface with super long 6.5 ft (2meters) cable. In this way, you can change your car battery, also by get the alternative 12V power source from another car, when you not have a jump starter on hand. 4、As our device with 2 meter cable, it will be a convenient way, should you not have jump starter (or Lead-acid battery) on hand, and the device can also get the 12v power supply from cigarette lighter of another good car. Just insert the Cigarette lighter plug to this car and INSERT IGNORE INTO 16 pin plug to the OBD port of the car you want to replace battery. 5、Great for keeping the computer memory alive while working on the car. Many repairs need to disconnect the battery and this connected to an external power source.