If you are using any 50L Keg coupler (A-Type, D-Type ect.) and want to be versatile in what kegs you can get, then we would strongly suggest converting your couplers to 5/8" Ball lock posts, to use ball lock disconnects on your coupler to change them over quickly. 
This is for liquid only, the identifying difference is a smooth finish, no engraving band around the postengraved band around the post. A Liquid Ball lock will only fit on a liquid post.
We would also recommend using some Keg Lube around the liquid posts to prevent beer from drying and making it hard to get the disconnects off the coupler in the future.
Features:
- 304 Stainless Steel
- Complete plug and play - Complete with seals, poppet & spring