The JBL Tune 520BT headphones produce a powerful JBL Pure Bass sound thanks to the latest 5.3 BT technology. Use them without limitation as these headphones for iPhone or Android produce up to 57 hours of exceptional JBL sound and for more you can charge just 5 mined to get an extra 3 hours of battery life. Download the JBL Headphone app and manage your playlist via EQ while being guided by Voice Prompts Guide technology. Manage calls, sound, and volume from the headphones via button control. If you receive calls while watching a video on another device, the JBL Tune 520BT instantly connects to your phone so you never miss a call. Lightweight and super comfortable, and after hours of listening, the JBL Tune 520BT headphones fold into your backpack to be with you everywhere .