During the maturity, stage sales will plateau, and the profit margins of your products will begin to decline. This is typically caused by a number of factors come this can be market saturation or other alternative solution to what said product implements (especially because competition of products can highly dependent on the price of service/product). Mature markets I believe are a good time to be prepared for to have an innovative solution to implement. A solution that could find an alternative market where similar tech can use. The maturity stage is also the time to start planning and researching for a next-generation product or technology, its good to either start this process well in advance and never too late into this phase or in a decline. Invest in market research is key and should happen periodically.