ok found this while searching aero ports 3" and 4"

[sho_me]

I don't know if anyone is looking for these or not but i found thise site don't know if its legit or not but here it is

http://www.rtboxes.com/accessories-aero-ports/

3" dia. 12.95

4" dia. 15.95 both are dual port flange

[Ben Building]

Great price! It would be nice to know if this is legit.

http://www.patentstorm.us/patents/5623132/description.html

Or are they beginning to encroach on somebody's patent? It that is the case, don't expect to see them for long.

[01 S-10]

They look like my precision ports. Not aero ports