So, Racked my first batch of experimental blueberry into my experimental 1 litre jug today - I actually got these from my parents - clean, used a billion years ago and came with screw top airlocks.. No problem. sanitized the "carboy" - racked my gallon of wine into it and pressed out the fruit.. then went to fit the sanitized screwtop airlock... snap... the screwtop lid plastic had pretty much completely deteriorated... There were 4 in the box, and checking them they were all bad.. any pressure would break them to bits..
Fortunately a 6 1/2 bung fits in there just fine..