Built-in internal battery from a commercial product. Used only once. Similar products are also listed, but this product has a built-in battery, allowing tracking even when the engine is turned off. Products without a battery are completely non-functional when the engine is off. This is a cigarette lighter-type tracking device made by Omegatech. You can track your car's location using the Find My app on your iPhone, making it easy to find where you parked in a parking lot. This commercially available product has a built-in battery and can track for 3 months even when the engine is off. Please see below for detailed product information. https://amzn.to/4amTaiY