A shoe horn is a tool that lets the user put on a shoe more easily. It does so by keeping the shoe open and by providing a smooth surface for the foot and the heel to move, without crushing the shoe’s counter (the vertical portion of the shoe that wraps around the back of the foot), in this way acting as a first class lever. Originally, shoehorns were made from animal horn, or hooves, and some made from bulls hooves are still available for purchase. There are various sizes of shoehorns, though the basic shape varies little except for the length of the handle. Long handled shoe horns, for example, are necessary for longer boots, and also used to reduce bending and straining by persons lacking joint mobility (e.g., older persons), while shoe horns with sturdy handles are useful for putting on boots or heavy iron shoes.