Vanishing Series RT speakers are timbre-matched to Polk Rti speakers to insure utterly seamless blending from speaker to speaker in systems that combine traditional and built-in speakers. Vanishing Series built-in speakers feature our exclusive wafer-thin Sheer-Grille, a magnetically-secured grille that protrudes only 7mm from its surroundings. Dual bandpass bass ports are highly efficient in small enclosures, and smoothly funnels the angled woofer's low frequencies down around the driver array