The most recent 5.3 BT technology allows the JBL Tune 520BT headphones to stream powerful JBL Pure Bass sound. These headphones are simple to use, offering up to 57 hours of uninterrupted enjoyment and an additional 3 hours of battery life with only 5 minutes of charging. Use the free JBL Headphones App to adjust your sound using the EQ and navigate the features of the headphones with the help of Voice Prompts. Use the handy button control to control calls, sound, and volume from the earcup. To ensure you never miss a call, the JBL Tune 520BT seamlessly switches to your mobile device if a call comes in while you are watching a video on another device. Even after hours of listening, the JBL Tune 520BT headphones are comfortable and lightweight. They fold flat.