Sprenger Duo Pelham
It has elements of both a curb bit and a snaffle bit. In this respect a Pelham bit functions similar to a double bridle. A Pelham works on several parts of a horse's head, depending on which rein is applied. The mouthpiece acts when either the snaffle or curb rein is applied and puts pressure on the bars, tongue, and lips of the horse. The curb chain and design of the mouthpiece can alter the degree of pressure placed on the horse's mouth. The roof of the mouth is affected if the bit mouthpiece of the Pelham has a high port or if it is jointed. Pressure onthe poll occurs when the curb rein is engaged, and pressure is directly related to the length of the upper shank (purchase arm) in relation to the lower shank (lever arm). All Pelham’s apply some pressure on the poll. Pressure is applied to the chin groove by the curb chain when the curb rein is used. Direct rein pressure from the snaffle rein may put some pressure on the sides of the horse's mouth, depending on the specific bit design.
Rubber and hard plastics are used to encase a thin core of metal on some bits. These bits are generally thicker than many of the metal bits. Some horses might appreciate the softer feel of a rubber or plastic mouthpiece, while others may find them an uncomfortable mouthful. You may find older plastic or rubber mouthed bits give off a funny smell which your horse might or might not notice. Many plastic mouthed bits are made with a scent that is thought to encourage the horse to accept the bit more readily, but this may encourage some horses to chew the bit and not carry the bit quietly. Both rubber and plastic mouthed bits do wear over time, sometimes quite quickly, leaving rough spots or exposing the metal core.
A bit that is made of hard rubber or a half-moon of metal, it places even pressure on the mouthpiece, lips, and bars of the horse’s mouth. It is a very mild mouthpiece.