Polk Audio TL150 Speaker (5-pack, Black) High-performance 5-piece surround system TL1 satellite aperiodio-tuned rear port TL1 center channel-tuned rear port .5 inches silk-dome tweeters Time lens technology Time lens technology-the acoustic centers of the tweeter and mid-bass driver are located in the same plane for superior imaging TL1 satellite aperiodic-tuned rear port enables better blending with a subwoofer TL1 center Channel tuned rear port maximizes the low end response of dual driver design for superior blending with the satellites and the subwoofer 2 1/2" Long-throw drivers with dynamic balance driver technology. 1/2" Silk dome tweeters for crisp, clear imaging and smooth response that's never tiring. Time Lens Technology-The acoustic centers of the tweeter and mid-bass driver are located in the same plane for superior imaging TL1 Satellite Aperiodic-Tuned Rear Port enables better blending with a subwoofer TL1 Center Channel Tuned Rear Port maximizes the low end response of dual driver design for superior blending with the satellites and the subwoofer 2 1/2" Long-Throw Drivers With Dynamic Balance Driver Technology. 1/2" Silk Dome Tweeters for crisp, clear imaging and smooth response that's never tiring.