Headphones Functionality: More than safety ear muffs, they are also headphones, you can enjoy music during downtime via Bluetooth or 3.5mm audio input (3.5mm cord is included). No batteries required, the rechargeable battery lasts up to 30 hours after each full charge. The knob allows you to control the volume level with ease (Line-in mode only). Built-in mic and integrated controls let you make and take phone calls without removing the earmuffs. Made for Lasting Comfort: Mpow noise reduction ear muffs are extremely well constructed and reasonably comfortable. With soft foam ear pads and skin-friendly PU leather, the ear cups fit snugly around your ears. The cups of these earmuffs are deep and have enough space inside the cups. Weighing onl... .