Stage1 621 The Stage1 Series speakers brings a concert experience to your car, truck or SUV. Their Polypropylene woofer provides a strong performance with great low end extension and clean tight midrange. The woofer is couple with a Mylar Balanced dome tweeter which fills out their sonic signature with crisp, high-end frequencies. Power Handling35Wrms, 175W peak • Nominal Impedance4ohms • Sensitivity (@ 2.83V)90dB • Frequency Response 55Hz – 20kHz