This is a BRAND NEW replacement cap for a home brew barrel with a 2" top. It comes with a S30 gas injection valve and a new 2" 'O' ring. It will fit most 2" top barrels out there so if you have brought a barrel and for some reason it didn't have one of these valves fitted when new then this cap will allow you to inject CO2 gas by means of a S30 gas cylinder - it won't operate with 8g or 16g bulbs.
This valve will not operate with the 8g or 16g bulbs.