Polk Audio RM6900 5.1 Channel Home Theater Speaker System (Set of Six, Titanium) 6-piece home theater speaker system with 4 satellite speakers, center channel speaker, and powered subwoofer Single center speaker uses two 3.5-inch midrange drivers and a 0.75 silk/polymer dome tweeter Satellite speakers use a 3.5-inch midrange driver (dual for fronts, single for rear) and a 0.75 silk/polymer dome tweeter Powered subwoofer is equipped with a 12-inch driver and slot load bass vents Satellites are magnetically shielded for safe placement near other electronic systems