Generic toothbrush holder, the gap between the two prongs is approx. 12.5mm so it should accommodate the majority of toothbrushes. (you can scale this to whatever size you need i guess)
As you can see it fits Oral B electric toothbrushes swell as generic toothbrushes.
I attached this to my wall with double sided sticky foam, it holds really well and gives it a little play so that it is not fixed solid to the wall.

Thanks for looking :D