observer fittings?

Does anybody know where I can get my hands on some observer fittings? I've seen them at the various brewery's I've visited and I have been wanting to install one in my homebrew setup because I use a stainless fermenter and opaque tubing so and I really want to be able to see my beer as I'm brewing it!

So far the only place i've seen them is in the Perlick catalog. http://www.perlick.com/pdf-files/newOBSERVERS.pdf. Does anybody know of any other place I can get them?

http://morebeer.com/view_product/11074/103723/Ultimate_Yeast_Harvester

I dont think its exactly what you are looking for but it looks pretty nice.

http://www.ebay.com/itm/200613346150?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Cheapest price i've seen but you will have to get some tri clover fittings for each side and the clamps.

Is there somewhere I can find more info on those Perlick ones, or even somewhere to buy them?

Maybe somebody can help me along the same lines - I'm looking for something similar, with an ID at least a little bigger than the OD of a typical airstone, ideally with NPT fittings. In case it isn't already obvious. I intend to use it with an inline oxygenator, to be able to ensure it's bubbling through properly.