Bluedio B2 Bluetooth Stereo Headset for Mobile Phones - Retail Packaging - Blue 1.Just for the color. We use PC+ABS material crafted with 2 coated 5 grilled procedure, to ensure color material was isolated from the air, make it lasting for years. 2.Long-lasting comfort. Ear cups of B2 are composed of artificial protein leather, suitable to wearing for long time. 360 degree rotation ear pads, are best to fit your ear. 3.Foldable and stretchable design. Foldable design of B2 makes the headset becomes compact, easy to carry for your outdoor use. Thus, you may adjust the headband to most appropriate length for your wearing. 4.Drive units made for pure sound.With 2 40mm, 50 built-in drive units inside B2, it has a special cavity structure to ensure smooth air flow, and detailed sound output to your ears. 5.Perfect sound and talk.B2 is composed of latest Bluetooth 4.0 chipset from CSR(the UK) to transmits high quality wireless music and clear human voice.