The tecnifibre court are pressurized tennis balls that can be used on all court surfaces and provide a blend of speed and feel as well as improved strength and durability ensured by grand touring formula rubber they have an approval of the international tennis federation itf and french tennis federation ftf and will be clearly visible from all areas of the court due to fluoro felt the balls come in a 12 dozen pack 36 pressurized cans of 4 balls each