As a general rule the thinner the mouthpiece: the more severe the bit and the smaller the rings: the more severe the action of the bit.
One of the main considerations when choosing a bit is the conformation of the horse's mouth. Some horses like ID crosses and Native crosses have quite fleshy tongues so need a bit that allows room for the tongue to lie underneath. Some Thoroughbreds can have low palates and ponies usually have quite a narrow bottom jaw. These things need to be taken into consideration alongside what action you actually want from the bit when making your choice, because, no bit will do the job you intend it to do if it is uncomfortable for the horse.
To help you in your choice, one of the UK's leading authorities on bits and bitting, Hilary Vernon, has produced an excellent illustrated guide... see panel on right...
Amongst the reletively new innovators in equine bitting, Neue Schule, have developed a range of anatomically designed bits, catering for different mouth conformations, using a range of new materials (like: Salox, Sweet Iron etc) for the actual mouthpiece. Modern bits, whether traditionally crafted or anatomically designed, are available in a range of materials which can be more accepable to the horse... such as: German Silver, Sweet Iron, Copper etc. These are a warmer metal than stainless steel and encourage the horse to salivate, encouraging a softer, moister mouth and more acceptance of the contact.
We have had great success with, and are a great fan of - Neue Schule and Sprenger bits.
