Automotive computer memory retaining tools are designed to maintain the memory of the on-board vehicle computer (ECU) when the power source (battery) is disconnected. Use of these tools when changing or interrupting the power source prevents loss of certain drivability codes, key-less entry codes, digital radio setting, cellular phone settings and other memory related functions. It also prevents loss of radio function on anti-theft radio systems. It"s handy to have and simple to use.