when I read this I was like what the...... Tom thubs arent harsh bits - the ones we use here in NZ are no harsher that a standard snaffle so am guessing that it is a different bit that we call a tom thumb
This is what I would call a tom thumb:
The first one is a Fulmer snaffle. They are both snaffles. Neither of these are tom thumb bits. They are not curb bits.