Subwoofers: What Are They & Do You Need One for Your Sound System?
One unit (not pair) |15 Inch Woofer for Bass Compensation of Open Baffle or Cabinet | W-15 - Lii Song (Lii Audio), unique speaker, amplfier, quality and cost-saving parts for HiFi DIY
What are the differences between a subwoofer and a woofer? Which is better? Can I use a sub instead of awoofer or vice-versa? - Quora