Highest quality stainless steel will last a lifetime. For the gas side of a ball-lock keg (you can tell by the grey ring around the base, the beer side has a black ring). This fitting features a ¼" hose barb. 2.25" tall.
These fit modern kegs only: If you have older USA made ball lock kegs, you will find this ball lock fitting does not fit as it is machined a bit tighter than the old standard. These fit KegLand, AEB, Old Ale,Torpedo, and other modern kegs, BUT DO NOT FIT OLDER CORNELIUS, SPARTANBURG, FIRESTONE, ALLOY PRODUCTS, AND OTHER OLD UNBRANDED KEGS.
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Jun 28, 2018 by Dan
Q: Will this fit 3/16 tubing or does one need an adapter?
A: The barb is 1/4" but we find if you put tubing in boiling water for a few seconds you can work 3/16" tubing onto this barb.
Jan 08, 2018 by Benjamin
Q: Is this barb the correct size for 5/16" inside diameter gas tubing?
A: No, it is for 1/4" tubing. If you add our item D08 to this, along with a D87 Concave Washer, it will fit 5/16" tubing.

Built Like A Tank
I've purchased these in the past. An outstanding product that will last for ever.
Heavy duty
I bought this because I had a leak on my kegerator. These still leak, but at a much lower rate. William's Brewing Responds: If you have a leaky ball lock fitting that leaks when a ball lock disconnect is attached, the Keg Fitting O ring may be worn or damaged. See our item D12 for a replacement.
Awesome
I knew these were great, but I didn't even know how great they were until I was talking to a friend about his plastic ball lock issues. You'll never have a problem with these, they will last forever. I'm a big fan of buying everything stainless, you get less problems in the long run.