By continually introducing new aesthetics, and retargeting or discontinuing older designs, a manufacturer can "ride the fashion cycle", allowing for constant sales despite the original products remaining fully functional. Sneakers are a popular fashion industry where this is prevalent - Nike's Air Max line of running shoes is a prime example where a single model of shoe is often produced for years, but the color and material combination ("colorway") is changed every few months, or different colorways are offered in different markets. This has the upshot of ensuring constant demand for the product, even though it remains fundamentally the same.