The main purpose of a full cheek bit is to exert lateral pressure, this emphasis on the turning aids is especially useful for young horses. The arms of the bit prevent the bit from being pulled through the mouth. Keepers, also known as Fulmer loops, attached to the upper arms, help stabilize the bit and offer a slight leverage action.
The double jointed bit consists of three parts. The middle section of the mouthpiece lies flat on the tongue, this causes more pressure on the tongue than a single jointed bit. The thicker the middle section, the more pressure it will create on the tongue.