Tripp Lite's Premier Mobile Theater Speakers bring sound to life with dual cones and 3D 7.1 virtual surround sound. PRODUCT FEATURES: Dual speaker cones deliver crisp, clear sound; Digital audio signal with 3D 7.1 virtual surround sound produces superior small speaker performance; Self-powered USB 2.0 interface eliminates the need for an external power supply; Lightweight, compact design and included carrying bag provide maximum portability while traveling; Included stands provide maximum placement for the highest quality surround sound.