The post on this unique carbonation cap has been machined to fit BOTH the black/liquid and grey/gas ball lock disconnects. This carbonation cap also includes a barbtail on the underside so you can attach some beer line to act as a dip tube.
This allows the carbonation cap to be used in several different ways including:
1. Carbonate PET bottles
2. Cleaning your beer lines
3. Use it to counter pressure bottle fill PET bottles