It appears that he is selling a "pair" and not just one?
I recently picked up some 511bs with 808 8b drivers. I'm really liking the sound from these horns. They are mounted from the front flange and supported 2/3 back from the front flange on the under side. I haven't noticed a problem with ringing but I was thinking of applying sound deadening material just to see if I could hear a difference. I know some have removed the vanes but I think it would narrow the sweet spot too much. Sorry, a little bit off subject. Just wondering how much effect the aquaplas has on 511s?