RE400i features a 8.5mm coated Titanium driver custom designed and manufactured by HIFIMAN. Superb fit and comfort in a compact size. Utilize special Titanium coatings for remarkable detail and extended frequency response. The addition of Neodymium magnets and premium cabling of Oxygen-Free Copper on RE400i helps deliver all the music as it was originally intended. Convenient hands-free design allows you to talk on the phone clearly and safely at your home, office or on the road. Consumer Alert: For Your Protection HIFIMAN products are sold through carefully selected, authorized retail partners to ensure the highest levels of professionalism and service. HIFIMAN products not sold by us, or one of our authorized partners, cannot be verified as authentic and will not receive the HIFIMAN manufacturer"s warranty or factory service. Before purchasing, please verify that you are dealing with an authorized HIFIMAN retail partner. You can do that by checking our official website. Help us help you.