Surround Effects loudspeakers are optimal for rear/side surround sound in 5.1 and 7.1-channel home theater applications. The CM7FX is designed for use with Niles CM7HD, CM7PR, CM8HD and CM8PR left/center/right loudspeakers. Glass fiber woofer cones and dual Teteron tweeters on a multi-axis array provide ultra-realistic surround sound effects.