Looks like it's called a threaded director, but here's the bad news. I just checked the Nylex catalogue and doesn't look like they supply the nut and washer plus the fitting no longer looks to carry a shoulder so there'd be nothing to home against. In fact, doesn't even look like the same dimentions on the one I have 
Mine came from Mitre 10 and I don't know if it was the Nylex Gardena product, but I sure can't see it in this catalogue http://www.nylex.com.au/prod_cat/MMC207 ... x_D794.pdf
If you scroll down through that catalogue until you get to page 12, you'll see a Male Threaded elbow with a shoulder on it, which is missing on the Threaded Directer pictured below it. But again, no nuts or washers pictured.
I'm now using a bigger tun and run the copper pipe through the drain plug as in this link http://brodiescastlebrewing.com/index.p ... 9#msg10819
You might need to go to a plumbing supplier with the cooler and let them know what you're trying to acheive if you can't find something suitable at a hardware.
Cheers, Ed
