The Mullen mouth is a very mild bit. It is an unvarying mouthpiece which means the pressure on the mouth doesnt change very much, as it is a fixed mouthpiece. The bit puts pressure on the tongue and lips (corner of the mouth), it does use slight pressure on the bars depending on the size of your horses tongue. This bit is very useful for those horses who have a very soft mouth and dont like complicated mouthpieces. It may also be useful for horses who back off the contact and need that extra bit of confidence in the bit. This bit would not be suitable if your horse leans on the bit or if they tend to take hold of the bit, also may not be suitable for the breeds with larger tongues as they may find this uncomfortable. Ref: UTBZ2375