Girth (tack) often used in addition to a regular leather girth. Made of leather or nylon with an elastic insert (for racing), the overgirth completely encircles the horse around belly and the saddle's seat. It is used by stockmen, eventers, polo players, in flat racing, and by steeplechase jockeys to provide more security in holding the saddle in place. Some girths (those used on jumpers and eventers) have a belly guard (or stud guard), to protect the belly from being stabbed by horseshoe studs as the animal tucks his legs up underneath him over a tall obstacle. The traditional western cinch was
Girth (geometry) width, with the same width "w". All curves of constant width have the same perimeter, the same value "w" as the circumference of a circle with that width (this is Barbier's theorem). Therefore, every surface of constant width is also a surface of constant girth: its girth in all directions is the same number "w". Hermann Minkowski proved, conversely, that every convex surface of constant girth is also a surface of constant width. For a prism or cylinder, its projection in the direction parallel to its axis is the same as its cross section, so in these cases the girth