Bluetooth sync with mobile devices. This set contains 2 x Walker's Razor Slim Quad Electronic Earmuffs with Bluetooth Technology (Black), Limited 1-Year Warranty, 2 x Walker's Razor Tactical and Hunting Walkie Talkie Attachment, 2 x Walker's Crosshair Sport Shooting Glasses (Clear), and a 2 x Top Brand High Quality Microfiber Cleaning Cloth.