wanna call me a dumbass huh? Now I'll take it personally. Your lucky I dont have my notebook with me at work from the 15+ coils i have in my garage and I would show you how completly and utterly wrong you were.
Is ID all that matters ? how about the OD of the coil You said width, which you say is 1.4", but that would make the coil 4+ inches. what I assume you meant was 1.4" tall. and the winding width, since it is a 4 layer coil I would expect to be around a half inch.
there are thousands of subs out there on the market, and many of which say "3 inch coil" most of which use a nonstandard 3" Chinese coil which varies with whatever former happens to be the cheapest at the time.
Also how can your 3" recones be universal when spiders vary on most baskets. Also how are your recones going to be universal when the motor strength of every subwoofer is different. You goign to use 2 cotton spiders on a spl sub, like a btl? then if you could get the coil to go over the former, it would slam into backplate so hard it would break the former off and blow the nice universal 3" recone.
If you want I can show you some more flaws in this universal recone.