Bytech BTPOP Mini Portable Pocket Speaker ERCD - Expansive Resonator Construction Design to give the best low frequency output Compatible with iPods, iPhones, MP3 players, laptops with 3.5-mm audio socket, Android smartphones Full-bodied, 360-degree sound with modular design 40mm driver Ultra-portable compact size with long-lasting internal rechargeable battery Connect Multiple Speakers for Maximum Sound