Any player, any surface, any time these promotional tennis balls by Wilson are a great choice out on the court. They come in tubes of 4 cans with exclusive Dura-Weave felt that offers superior performance on all court surface types. They have a high altitude core for best performance on courts about 3500ft and will work well on clay courts and outdoor surfaces. The Wilson Championship balls are opened for printing purposes and therefore no longer pressurised. Pricing shown is per ball with a long-lasting durability print.