Products of fashion, by definition, have a shorter life cycle, and they thus have a much shorter time in which to reap their reward. A distinction is sometimes made between fashion items, such as clothing, and pure fads, such as the notorious pet rocks. It is not always immediately obvious into which of these two categories a product falls. When they were first introduced in the early 1980s, in-line skates seemed as if they might be a brief fad. But 25 years later they were still selling strongly, firmly set in the mature stage of their life cycle. They may not be destined for the life cycle of the corn flake, but they have already outlived many seemingly more permanent products.