Western stirrups are designed to hold the foot of a rider, attached to the saddle by a strap, often called a stirrup leather. Stirrups are used to aid in mounting and as a support while riding a horse. The branches (sides) are wide at the bottom and narrow at the top, where they are joined by a heavy dowel of wood, or rod of metal. The stirrup leather loops under the rod and a "keeper" (a strap with a buckle that wraps around the front and back of the stirrup leather), keeps the stirrup in place. Western stirrups are usually made of leather-covered wood, others of steel, aluminum, or even very strong fibre-reinforced plastic. They are designed to parallel the use intended by the design of the saddle itself.