I have had one attached to my nappy bag, and another attached to my ergobaby carrier. It fits a single dummy nicely (I am using the Avent Soothies).
They secure well with a plastic snap and the strap is long enough to go around most bag handles.
Its a bit tricky to open it one handed, but I have managed to do this with a little dexterity.
It does exactly what its supposed to, and looks nice as well.