A shoe tree is a device approximating the shape of a foot that is placed inside a shoe to preserve its shape, stop it from developing creases, and thereby extend the life of the shoe. Perhaps more important than maintaining the shape, shoe trees also play a crucial part in wicking away moisture caused by sweat - a major cause of lining rot and leather degradation. This is especially important when shoes are worn without socks. Higher quality shoe trees are made from softwood, usually cedar, which helps control odor and absorb moisture. Types Among wooden shoe trees, there are generally three categories, which correspond to price and quality. Spring shoe trees The cheapest are a wooden shoe tree without a full heel. Although they help with odour, and will help preserve the original shape at the front of the shoe, the narrow knob on the heel puts excess pressure on one section of the heel and prolonged use may deform the shoe. Notwithstanding, this style of shoe tree is popular with high heels because of its flexibility. Generic shoe trees Generic shoe trees are non-lasted shoe trees that are designed to fit a wide range of footwear styles. Generic shoe trees come in many styles; two of the more popular ones are the twin-tube and single-tube shoe trees. The twin-tube shoe tree, cut from a generic last and featuring a fully articulated (round heel), a spring toe, and ventilation holes. This style is most popular in England and Europe. The single-tube, split-toe shoe tree with an overhand handle, works on a spring-spreader mechanism, causing the split toe to expand into the shoe when inserted into the shoe. This style is most popular in the United States. Lasted shoe trees At the highest range are lasted shoe trees, which accompany the shoes for which they have the same last. Plastic shoe trees Shoe trees may also be made of plastic or stamped sheet metal, with or without a coiled steel spring stem; these are typically cheaper, lighter, and are better suited for traveling. Types lacking a flexing steel spring may use extension springs or adjustable two-piece stems having an over-center mechanical action to wedge them in place. Plastic shoe trees maintain the shape of your shoes but lack the moisture-absorbing qualities of wooden shoe trees. Because wooden shoe trees can damage the leather when stored in luggage, plastic shoe trees