Girth (tack) slightly too small, a girth extender may be used. A girth extender attaches to the billets of the saddle and lengthens them, so that a shorter girth may be used. Most jumping saddles have three billets. This not only allows the rider a spare should one break, but can also provide an adjustment option. For horses on which the saddle sits nicely, neither slipping forward or back, the first and third billets should be used. On horses where the saddle slips back, the first and second billets should be used. The second and third should never be used together, as
Tree girth measurement known to approximate the measurements: 1) distance of the camera from the tree, 2) distance from the camera to the scale, and 3) size of the object to be used as a scale. An Excel spreadsheet can be used to determine the rate the apparent size of the scale changes with distance, and that value can be used to calculate the diameter of the tree given that the tree is circular in cross section and the distance to the front side of the tree is known. Girth then is calculated by multiplying the diameter by pi. The method may be