Can this be used as a cool tube?

http://cgi.ebay.com/PYREX-Corning-BA...QQcmdZViewItem

+ 4" inline fan...

Eh?

They are 4" round and only work for HPS lights; MH will not fit in the glass.
I use exactly the same thing for my 1000w HPS lights. You will need 2 4" collars some aluminum foil tape, 2 eye bolts 1 mog socket, some piece of metal to hold the mog socket in place, 2 4" hose clamps, and 3/8" foam tape. That is how you make a cool tube out of a bake around.

Very nice.

Thanks a lot you two. This might turn intio a project soon.