Quantum QB503 Beta Series 5.25 Inch 3-Way Speaker 5.25 Inch 3-Way Speaker, Piezzo Dome Tweeter, Mylar Dome Tweeter / Mid PP Cone, Ferric Oxide Magnet, Rubber Surround, Stamped Heavy Gauge Basket Max power: 140 Watts, RMS power: 40 Watts Sensitivity: 91dB , Freq. response: 50Hz - 25KHz Magnet size: 12 oz Ferric Oxide Magnet