As a piece of equestrian equipment, what function is served by a "numnah"?

A numnah is similar in function to a saddle cloth, however, it is more like a saddle pad. Essentially the main difference between a numnah and a saddle cloth is the fact that a numnah is shaped around the saddle, and a cloth is usually a square piece of material. Numnahs fit snugly beneath your saddle so that only a small part of the material is visible to any onlookers. Seeing as less material is covering your horse, they may be a better option during the hotter months. However, most people choose between a numnah and a saddle cloth based on personal preference.