PreSonus Eris E5 Studio Monitor Pair - Buy One Get One 1/2 Off 5.25-inch Kevlar low-frequency transducer 1-inch (25 mm), ultra-low-mass, silk-dome, high-frequency transducer 70 watt Class AB biamplification Front-firing acoustic port for superior bass-frequency reproduction RF interference, output current limiting, over-temperature, transient, and subsonic protection