Tom Thumb Bits have a jointed structure that causes a nutcracker action in the horse’s mouth. This makes the horse toss its head upward which can be very unsafe. These bits have a broken mouthpiece with medium shanks that provide a leverage action. This mechanism applies pressure to the top of the horse’s head as well as on the chin. In case the reigns are pulled harder, the mouthpiece moves upwards and hurts the roof of the horse’s mouth. This is where it becomes bad for both, the horse and the rider. However, riders who have learned the art of managing a Tom Thumb Bit will disagree. If used correctly with the right precautions, these bits are not as bad as they have been labeled.