B&C 21DS115 is a very high power 21" subwoofer for speaker subwoofer systems- B&C 21DS115 21" Subwoofer has a lightweight neodymium magnet - B&C 21DS115 21" high power speaker for speaker subwoofer
B&C Speaker 21DS115 4Ω - 21″ Subwoofer
B&C 21DS115-8 21" Neodymium Subwoofer 3400 Watts Program 4.5" Coil 8-Ohm Pro Sub | eBay
Outdo B&C 21DS115 and upgrade to modular subs - Speakerplans.com Forums - Page 6