Susan are you asking about the little tit on the end of the tensioner that can push in if you push on it? If that is what your asking about, yes it is. That is the pin that when you lift the presserfoot bar it automatically disengages the tension assembly. Be very careful not to loos this pin!!!! It will come out and you need to take it out to clean it but just remember to put it back in before you put the tensioner together again.
Billy