The quarter keg (pony keg) is also used in two variations that are the same capacity but have a slightly larger 17" diameter. These are the rubber-sided version and the bulged non-straight wall version (Molson-Coors Brewing Company).

The availability of each size of the keg will vary by brand of beer and location. It would be best to ask your beer supplier to determine which brands of draft beer are available in your area for immediate pick-up, which ones need to be special ordered, and in which size keg those particular brands are available.  

When contacting your local draft beer supplier, keep in mind that they typically stock only the most popular beer brands and keg sizes. However, local draft beer suppliers typically receive weekly deliveries from beer distributors or breweries. If the brand or keg size you want is available, and if you give them a few days' notice, they are usually happy to include it in their next delivery.

As there are literally tens of thousands of breweries and brands of keg draft beer available, it's simply not possible for Micro Matic to maintain a listing of the sizes of keg or area in which each brand of draft beer is available. It is vital not to kink the beer hose as it leaves the coupler. This will restrict flow and cause foaming.  

In general, at least 5" to 6" of clearance needs to be allowed above the keg for the keg coupler and beer hose. If you have limited space, an elbow fitting can be used to reduce the clearance to 4". In applications where there is hardly any clearance available, a low profile keg coupler requires only 1" above the keg to be used.