These boot insoles have a layer of memory foam that forms to the shape of your foot for custom comfort. The memory foam extends the length of the insoles so it cushions your entire foot. Under the memory foam, the insoles have a polyurethane layer for maximum cushioning as you stand or step. The heel cups provide comfort and support to your heel area. On the underside of the comfortable insoles are airflow channels that push air to your feet as you walk, helping to cool your feet. Size: M (6-8.5), L (9-10.5), XL (11-12.5), XXL (13+up). Material: Synthetic.