A curb gag is similar to a gag bit but has a different effect. The pressure isn't behind the ears but on the lower jaw. The string runs under the chin and the cheekpieces are attached to the extra ring at the top. This bit is effective for strong, hot horses and is mainly used by showjumpers. This bit is not suitable for inexperienced riders. An eliptical (double-jointed) mouthpiece is a standard mouthpiece.This mouthpiece has two hinges, is shaped more towards the mouth and lies somewhat looser in the mouth. This bit exerts pressure on the tongue, the layers and the corners of the mouth. Be careful with narrow lower jaws, the hinge points can press on the bars which can cause wounds. Compared to a single jointed bit, this bit exerts more pressure on the tongue. The Sweet Iron bits are made of steel and have a recognisable blue color. Sweet Iron will rust when it comes into contact with (air) humidity, the surface rust tastes sweet and naturally stimulates the saliva production. This will cause the horse to salivate more, which in turn will encourage a better acceptance of the bit.