9921b: 1500w to 2500w - 21 Inch Power Tuned Subwoofer - DD Audio
Apocalypse DB-SA521 NEO | 21 inch Subwoofer
BASSBOSS VS21-MK3 2,500-watt Single 21-inch Powered Subwoofer | Sweetwater
21" Competition grade Hand Built Subwoofer 8000rms (Super Team) - EM Audio Subwoofers
MT21A Built-in DSP single 21" Self-powered Subwoofer with Compact Cabinet Box - Buy 21" subwoofer, single 21 inch subwoofer, self powered subwoofer Product on Sanway Professional Audio Equipment Co., Ltd.
Dayton Audio HTS545HE-4 Kraken 21" High Excursion Subwoofer with 5" Voice Coil 4 Ohm
Eminence NSW6021-6 21" Professional Neodymium Tour Grade Subwoofer Driver
One unit (not pair) |21 Inch Woofer for Bass Compensation of Open Baffle or Cabinet | W-21 – Lii Song (Lii Audio), unique speaker, amplfier, quality and cost-saving parts for HiFi DIY