My mouthguard was fitted by a dentist which i really like to the point where I put it on earlier before I fight than I have to just because it's comforting (yes I have issues ).

I pay a monthly rate for private health cover which pays for a large portion of this so it wasn't an expensive thing for me to get.

For some reason I could never get other mouthgurads to fit properly and stay in - probably something I was doing wrong when I was trying to mould it.

The one I have has never ever fallen out.