Presonus Eris E4.5 2 Way 4.5 Studio Monitor Pair w/ Isolation Pads and Headphones 4.5-inch Kevlar low-frequency transducer 1-inch (25 mm), ultra-low-mass, silk-dome, high-frequency transducer Front-firing acoustic port for superior bass-frequency reproduction Optimized, resonance-suppressing internal bracing 100 dB maximum continuous SPL