This is the GAS IN keg coupling adapter for commercial keg couplers.

Used by home brewers who wish to use 50 litre pub kegs (keg couplers)  and still maintain standard ball lock connections on their tap/gun and C02 systems.   Fits both the flat and well type keg couplers.  5/8 female thread.

Adapter with gas ball lock  post  $10.50