These little items are essential if you're going to get any joy from your syphons. As far as I know, there's no other way of pressurising them. The thread was consistent over most of the years (but sadly not the same on new models!). I have a few of these spare, if anyone needs one, and will also buy any spares you might have. My favourite (sad isn't it!) is a beautiful polished steel version from (I suspect) the 40's. They are very hard to put a firm date to, if anyone has any information, please let me know.