Bluedio B2 Colourful Music Hi-Fi Rank Wireless & Bluetooth Headphones (Black) 1.Just for the color In order to make 5 colors(green, blue, yellow, white, black) of B2 Headset can be show perfectly, bring you ultimate experience. 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. Additionally, 1.5 days(33 hours) music playtime and almost 2 months(1300 hours) standby time, may let your color revolution through and through.