Eshion 3.5mm Portable Stereo Mini Speaker MP3 Player For Mobile Phone&Tablet PCS Size: 80mm x 30mm(3.15"x 1.18")(Length x Diameter) Dual channel, Mono Speaker. Powered by 2 AAA 3V batteries (not included). Compatible with all devices with 3.5mm connector, such as iPhone, iPod, MP3, MP4, etc. Compact speaker with built-in resonator expands to provide deep, full-range sound.