The Polk Audio RM6751 Satellite Speaker for RM6750, Titanium Finish (single) allows you to build an EX or ES surround sound system for 6.1, or 7.1 or more speakers. The integrated Power Port Bass Vent designed onto the back of this compact unit is the same technology used in full-sized Polk Audio speakers, and improves lower midrange response and all-important blending for a great performance at a reasonable price range. This integrated design reveals a midrange with no hole in the frequencies, for male vocals that are rich and full rather than thin and weak like many other systems.