Proficient AW525BLK Stereo Speaker; 5-1/4 Inch Dual Voice Coil Polypropylene Woofer, 2-Way, 88 dB Sensitivity, Black The AW525 plays all the way down to 45 Hz, low enough to reproduce bass with authority A pivoting tweeter made from Supernil synthetic fabric produces smooth highs and resists mold and mildew Waterproof drivers and super-tough ABS molded enclosure