Polk Audio LSi15 Left Channel Tower Speaker (Single, Ebony) A single tower speaker with mirror imaged speaker pairs for true three-dimensional sound imaging Equipped with two 5.25-inch dynamic balance aerated polypropylene composite drivers Contains a built-in 8-inch subwoofer for true full-range performance Equipped with one 1-inch high performance ring radiator tweeter 1.5-Inch side panels provide a totally inert enclosure