Review (1/5): Cheap and don't fit properly
I bought these for a Braun Oral B toothbrush. Never again! They don't fit properly - the O-ring at the bottom does not seal the heads to the toothbrush body, so a lot of water and toothpaste get trapped under the head, and then leaks out slowly during the day. A bit gross. Two of the ones I've used, brush itself partially separated from the head, creating a gap that pinched to the point of drawing blood.
They're cheap in price because they are cheaply made. Avoid them.