Where does one find this duct (flange) item? Best site for duct/cooling supplies?

Its the screw-on flange from homebox grow tents.

What is it? Where can I get similar? Best site for duct and cooling items?

Thanks.

Here is the link. I can't get a pic bc/it's flash.

Linky Here

http://www.homebox.net/dhtml/product_family_flange.php