Although some modern saddlers have developed alternative models, the English saddle is usually constructed on a framework known as a "tree". The tree is made of wood, spring steel, or composite, and it supports the rider on a sling of webbing between the firm "pommel" (front of the saddle) and "cantle" (back of the saddle). On either side of the tree, a steel hook known as the "stirrup bar" is affixed. It is upon this hook that the rider hangs the "stirrup leather", which is a very strong leather or nylon loop supporting the stirrup. More very strong leather or nylon straps known as "billets" (or "girth points/straps" - UK) are attached to stout webbing which is tacked across the top of the tree, to which will eventually buckle the "girth"--the beltlike strap which holds the saddle onto the horse.