Rubber stopper with center plug and 2,5-bar pressure relief valve for 5-liter mini Party kegs. Grey. Can be reused.UsageThe pressure relief valve opens automatically if the pressure exceeds about 2.5 bar, to protect the keg from too high pressure which might otherwise occur during keg conditioning / priming.When you insert the stopper in the keg, push down around the outer edge.If you push down on the center plug, it may fall into the keg.When it's time to start serving beer, push the dip tube of the dispenser through the rubber stopper. The dip tube seals against the rubber stopper and the center plug falls into the keg.