Designed for use during car battery replacement. When replacing the car battery, connect the alternative battery and car OBD2 port with this E60 ECU emergency power cable. To protect the car's ECU data. Unique design that has 2 methods to get power. Get power from a 12V battery with the clip connector, or connect to the battery box (8 AA batteries are required, batteries are not included) Power can be supplied from any 12V DC source, such as via a jump starter, a 12V lead acid battery, or a 12V DC battery from another car, etc. Package includes: an emergency power cord clip, a battery box (battery not included) MR CARTOOL E60 OBD2 memory saver cables are compatible with a wide range of vehicles equipped with an OBD2 port. This makes them a versatile tool for various car makes and models. Additionally, they are a cost-effective solution compared to more complex memory retention devices.