Well they do the job, but the rubber 'O' ring often slides down the short lug when the foot is inserted.
Also, it was not clear on the webpage for the speaker if they were included with the speaker itself. In fact they were, although I bought extra feet just in case.
This turned out to me a good thing to do, as when I hit one of them to get it into the fixing hole, one of the locating lugs broke off.