PA-014 21 Inch Overweight Subwoofer Speaker 125 Core 250 Magnet High-Power Outdoor Ultra-low Unit 1200W/8 Ω (1PCS) - AliExpress
Test Bench: B&C Speakers 21DS115 21-Inch Woofer | audioXpress
B&C 21SW152 is a very high power 21" subwoofer for speaker subwoofer systems- B&C 21SW152 21" Subwoofer has a lightweight neodymium magnet - B&C 21SW152 21" high power speaker for speaker subwoofer
B&C 21DS115-4 21 inch Professional Neodymium Subwoofer for sale online | eBay