Installed in the car battery for real-time monitoring through mobile phone app (free app for both iOS and Android). Receive notification of battery conditions when entering Bluetooth range. Displays voltage and charge status when user is close to the vehicle; no need to open the app. Automatic synchronization when entering Bluetooth range. Checks starting (cranking) system each time the engine starts; monitors starting voltage every hundredth of a second during engine start. Supports all 12V car batteries. Compatible with Android 4.3 and later, iOS 7.1 and later. Available for iPhone 4s and later, iPad 3 and later. Language: English Connection: Bluetooth Color: Black Material: ABS Size: 17x13x2cm Package Contents: 1 x Battery tester Only the above package content; other products are not included. Note: Light and display differences may cause slight color variation between the image and the actual item. Measurement error allowance is +/- 1-3cm.