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.
RCF SUB-8005AS Single 21″Active High Power Subwoofer – Sonic Circus
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
Eminence NSW6021-6 21" Professional Neodymium Tour Grade Subwoofer Driver