FX Wireless headset with Built-in Battery USB Charging Cable The New FX- Wireless headset with built-in battery Studio provides a 10-hour rechargeable battery. To prevent wasting energy, the Auto On/Off feature turns off the headphones when you unplug. Forget specialized adapters; the New Studio can be charged via micro USB almost anywhere. Features: Excellent Audio Easily Connect With Broad Compatibility Dual Mode With Or Without Audio Cable Hands-Free Call Function With Built-In Mic Extendable, Fordable, and Portable Easy-to-Use Buttons Ergonomic Design Specifications: Housing material: Plastic Power supply: Rechargeable lithium battery Battery voltage: 3.7V Battery charging voltage: 4.20.05V Rating power: 1.8W Frequency response: 100Hz, 20kHz Signal-to-noise: ?85db Distortion: