Definitive offers five compact Dolby AC-3* ready bipolar rear/side surround speakers (BP1.2X, BP2X, BPX, BPVX, and BPVX/P) intended for on-wall, shelf or stand mounting (you can also use any of our bipolar towers for rear/side surrounds) plus an in-wall bipolar surround speaker, the UIWBP/A). Like our center channels, they are built to the same high construction and performance standards as our main left and right front speakers and include features like high-definition bass/midrange drivers with butyl rubber surrounds, wide-dispersion pure aluminum dome tweeters with magnetic cooling fluid, complex Linkwitz-Riley crossover networks and solid monocoque cabinets with diffractionless grill/baffle interfaces.