Infinity RS152 Reference Series 2-Way 5-1/4" Dual Tweeter Surround Speakers - Pair (Black) 2-way 5.25" (130mm) on-wall surround loudspeaker Patented Hemispherical Soundfield Technology (HST) for consistent performance across a 180-degree area Dual 1" (25mm) CMMDTM (Ceramic Metal Matrix Diaphragm) tweeters with advanced waveguides 5" CMMD  Ceramic Metal Matrix Diaphragms sandwich an aluminum driver between ceramic layers, the ultimate construction for accuracy. Ultrarigidity means no unwanted coloration, while light weight cones pick up subtle detail. SLIPSTREAM TUNED PORTS use patented technology to improve bass performance. Curved, flared edges minimize turbulence, reducing port noise and delivering precise, powerful base.