Shoe trees are used to maintain and extend the life of your shoes. They serve several purposes:

1. Maintain Shoe Shape: Shoe trees help preserve the original shape and structure of your shoes, preventing them from developing creases, wrinkles, or sagging.

2. Absorb Moisture: Shoe trees can absorb moisture and odors, helping to keep your shoes fresh and dry. This is particularly useful after wearing shoes on a hot or rainy day.

3. Smooth Out Wrinkles: By filling out the empty space inside the shoe, shoe trees can help smooth out any existing wrinkles or creases, making your shoes look better.

4. Aid in Cleaning and Polishing: Shoe trees provide a solid form that makes it easier to clean and polish your shoes, ensuring a more even application of shoe care products.

5. Prevent Sole Deformation: They can also help maintain the shape and integrity of the shoe's sole, especially in leather-soled shoes.

In essence, shoe trees are an essential accessory for anyone who wants to keep their shoes looking good and lasting longer. They're particularly valuable for high-quality or leather shoes.