Frankly only shops I have visited fail completely in providing an indication about what exactly they are selling when it comes to keg fittings.
I have read this answer to another question, which was asking less generally then this, also about the fittings for keg connectors.
My question is: What are the different standards related to those fittings, what, and more over how can I measure which fitting I have?
Bonus: Is it only my impression that online shops do extremely poorly with regards to providing any, or if so accurate description about the fittings.
Part of an answer could also be which of those fittings sizes/descriptions like
MFL, actually exists, or are merely customarily used, but are not actually a "thing".