HiCool Bluetooth Headphones, M5 Wireless Bluetooth Earphones Stereo Sports in-Ear Headsets Sweatproof Earbuds Latest CSR Bluetooth V4.1: Advanced CSR 4.1 enables you to pair with all kinds of Bluetooth Enabled Devices with faster pairing speed. Supports 2 connections simultaneously. Lightweight and Magnetic: Ergonomic design offers you extra flexibility, portability and durability. Removable ear pieces along with flex sleeves make sure that it will never fall out during the exercise. Perfect Sound Quality: Built-in Dual speakers deliver you deep bass and crystal treble, endowing music better sense of space. Just enjoy the vigorous and beautiful sound. Anti-perspiration Design: The ABS and PC material blocks your sweat trouble, preventing the headphones from damaging. You can heartily asperse your sweat and passion. After-sale Service: HiCool will always be here for you if you have any problem. No worries for you after purchasing.