Patented Plus One Polypropylene Woofers Polypropylene cones with up to 35% more radiating cone area than other cones in the same class provide higher sensitivity, increased low frequency output and better tonal balance. Hi-roll rubber surrounds using automotive grade materials result in cleaner reproduction and higher durability whether it's easy listening or time to show and shine. Edge-Driven Tweeters Edge-driven tweeters deliver wider dispersion and smoother high frequency response with increased power handling for high- and mid-frequencies. True 4 Ohm Architecture True 4 ohm architecture with low impedance voice coils give the amplifier room to deliver peak power providing stronger and clearer sound with better depth and detail. Harman Standard Reliability Testing Infinity speakers have to undergo a testing process that would destroy lesser speakers. Infinity freezes them, bakes them, shakes them, blasts them with ultraviolet light and drives them at full power for days at a time. Voicing of Speakers Speakers are individually voiced to assure high quality audio versus "off-the-shelf" manufactured sound. This means that specifications as well as speaker characteristics are considered when tuning the Infinity sound.