Bluetooth Headphones, Marvotek Wireless Earbuds Sports Earbuds with Build-in Mic In Ear Headphones Stereo Headphones Sweatproof Black CSR Bluetooth chip with the advanced 4.1 version, support auto back-link, income phone ID broadcast and energy indicate on iPhone. Provide 10Ms transmission range. Feel free to use them across your room, gym and through walls. APT-X High Fidelity decoder technology, CVC6.0 newest noise canceling version, stereo channel design, provide you HI-FI sound quality. Built-in 3 sound effect modes: Pop, Rock, and Live which can be switched easily while playing music. Slanted ear buds design provides more comfort and fitness for excellent wearing experience. With an extra of 2 pairs of ear buds and 1 pair of ear hook, make it a best earphones for running. Glisten metalized ear buds shell with light reflect decoration make you look great while wearing. Pre-programmed smart English voice guide makes all function easy to use and support caller ID report. Built-in imported high definition Microphone support clear-voice hand-free talking. Built-in 80mAh lithium battery support 5H music time and 6H talking time. Take about 1.5H for charging. We are always striving to provide customers with high quality products as well as best services before or after sale. If you have any question before purchasing, please feel free to consult with us by sending email through the following steps on our store page: Click "Sold by Marvotek"-"Have a question for Marvotek?"-"Ask a Question". We are on call.