They are usually only SVC 2 or 4 ohms. These were custom made by Fi into DVC 4 ohms. They have 8 layer 3" coils. I have them in 12 cu ft with a Nine.1 at 1ohm. its pretty crazy and also sounds dammm good. Thats right, you dont have to use them in IB. They like large boxes though. If I gave them more airspace, they would like it a bit better. I also have ran 1 at 1 Ohm in 12 cubes and it sounded good too. Great all around subs guys. I can get you gusy some vids or something if you would like. Oh, and I will give you guys pics with my user name and all if anyone is interested around here. Lets start the prices off 300 + shipping. Here is a link to the specs https://ssl.perfora.net/www.ficarau...Speakers/0050_IB3/product_overview.shopscript