This is THE product to use for aging your beer on oak cubes, dry hopping, adding cacao nibs - any post-keg addition of ingredients you can think of! We have welded on a tab on the underside of a normal, used keg lid. To use, simply thread the string of your hop bag into the hole and tie off. When it is time to remove your adjunct/hops, pull the lid off of the keg and replace with a normal one. This really enables you to control the exact time your beer sits on the hops, oak, etc. and makes their removal a cinch!