Upgraded 5.3 Bluetooth Chip: UGREEN aux Bluetooth adapter for car uses the latest Bluetooth 5.3 chip, aiming to provide faster transmission speed, higher reliability, stability, and lower power consumption; offering clear calls, super Low static noise, and CD sound quality. | Hands-Free Calling & Sounds Clearly: The Bluetooth aux adapter for the car solves the inconvenience of making a call and the problem of unclear call sound while driving. Just press the big circle button to make a call and equipped with a built-in microphone can make you clearly hear the other voice. Providing you with the ultimate call experience, and also ensuring your safety. | Faster Charging and Superior Battery Life: The Bluetooth aux adapter has a battery life of 15 hours no matter whether making calls or playing music. It takes only 2 hours to fully charge the device by using a Type-C fast charging cable (Included in the package). | Convenient to Use: The Bluetooth aux can easily be used with car audio systems, speakers, amplifiers. Just plug the adapter into the 3.5mm aux port, and you can easily connect these devices to mobile phones, tablets, etc. | Dual Device Connection Supported: This aux to Bluetooth supports connecting 2 devices simultaneously. You can easily switch devices for calls and music while driving, and change music with your friends at parties. | Note: This is an aux Bluetooth receiver for car, it cannot be paired with Bluetooth headphones/speakers. 2. Do not work on planes. | What can I do if the adapter cannot boot? The adapter might temporarily turn off or be difficult to turn on in cold conditions. You can recharge it or just use a hair dryer to blow it for 1-2 minutes via the hot air, and then turn it on.