9921b: 1500w to 2500w - 21 Inch Power Tuned Subwoofer - DD Audio
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.
Sledge M6-21 6.0cuft Subwoofer Flat-Pack for 21" Subwoofers
Yorkville Sound ES21P Elite Series 21-inch 2400W Powered Subwoofer | PSSL ProSound and Stage Lighting
Eminence NSW6021-6 21" Professional Neodymium Tour Grade Subwoofer Driver
DS18 PRO-BX21N.2 21" Neodymium Woofer 6000 Watts 6" 2-Ohm SVC audio car home system Subwoofers
Amazon.com: Sound Town 21” 1000W Cast Aluminum Frame Woofer (Low Frequency Driver), Replacement Woofer for PA/DJ Subwoofer Cabinets (STLF-21500A) : Electronics
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
Passive Double 21" Subwoofer FL221
RCF SUB-8005AS Single 21″Active High Power Subwoofer – Sonic Circus
AccuGroove Whappo Grande Bass 21" Subwoofer – AccuGrooveLLC
Dayton Audio PSS555-8 21" Pro Subwoofer with 4.5" Voice Coil 8 Ohm