Just like the various materials bits are made of, horse bits come in many different types of bit mouthpiece styles. Here are descriptions of the most common types you may see when choosing a bit for your horse.
1. Mullen Mouthed Bits
A bit with a mullen mouth is a plain mouthpiece, with a slight curvature so that it sits comfortably over the horse's tongue. This type of mouthpiece will be slightly more comfortable for a horse to carry than a straight bar mouthpiece. The mullen mouth is thought to be a gentler bit than one with a jointed mouthpiece, as there is no nutcracker effect when the reins are pulled. Mullen mouths are seen on both snaffle and curb bits such as mullen mouth grazing bits, or English and western-style pelhams.
Examples of Mullen Mouth Bits:
Rollers can be made of stainless steel or copper, or are often seen in an alternating pattern as on this full check snaffle. The function of the cooper rollers is to encourage salivation, while the rollers themselves are felt to prevent the horse from leaning on the bit. The rollers increase the severity of the bit slightly. Rollers are also seen on bits with ports and spades.
Bits With Rollers
4. Jointed Mouthpiece
5. French Link Mouthpiece
French link mouthpieces have a flat peanut shaped link in the middle to make two links. The French link mouthpiece is thought to be milder than a single joint or mullen mouth and easier for the horse to carry. A lozenge bit looks very similar to a French link, but the straighter link puts more pressure on the tongue.
6. Dr. Bristol Mouthpiece
Also called a Doc Bristol, this bit has a flat link in the middle, and looks slightly like a French link. The difference is that the link is longer and set at a slight angle, so the edge of the link has more bearing on the tongue when the reins are pulled. Like the French link, the Dr. Bristol has a slight nutcracker action. A Dr. Bristol mouthpiece is more severe than a French mouth or mullen mouth.