This Review Title is Not stable on mounting shaft and the content is: This is my first electric toothbrush and was given to me by a friend to try out. I bought the new heads after carefully making sure I bought the correct replacement heads. The brush head does not sit down all the way when pressed on and it shakes when turned on. It is not stable and can easily come off.  For me, the spinning brush head is small so it doesn't have room for much toothpaste. Maybe it would fit better on some other model, but it is now not being used..There are other information for this review, one is This reviewer did purchase it and the other is 1 people think this review is helpful.