My horse has a shallow mouth and a big fat tongue. After years of experimenting with bits he'd just run thru (sorry, buddy), I've settled on a french snaffle--with three pieces--that lays over his tongue very nicely. The change in his attitude was amazing. He used to point his nose way up when I'd be bridling, now he reaches for the bit. Amazing what you learn about your horse when you hang on to them for 12 years (I've been using the french snaffle for 6 now).