Bitting rig rig." It is the use of additional reins such as the overcheck, or the use of leverage to place the horse's head in a set position that turns a classic surcingle into a bitting rig. Both a bitting rig and a classic surcingle with side reins are intended only to be used while longeing a horse. They are not to be used on a horse that is standing in a stall (though this is a very common type of misuse), nor are they used while riding. However, the surcingle and side reins are used as safety tools in the sport
Tree girth measurement is measured at a height of , , or . The base of the tree is measured for both height and girth as being the elevation at which the pith of the tree intersects the ground surface beneath, or where the acorn sprouted. On a slope this is considered as halfway between the ground level at the upper and lower sides of the tree. This "breast height" value is a measurement grandfathered from decades of forestry applications. It was developed because of the simplicity and ease of measurement. There is no one ideal height at which to measure girth. Tree