The Vollint Premier tennis balls offer a blend of high-performance and ultimate durability. They are designed for competitive play, match use and coaching and have a UK woven wool cloth for optimum playability on all court surfaces. With a durable rubber core and a thick, extra-duty felt, these premium pressurized tennis balls guarantee a longer lifespan and better resilience. Due to their lighter weight and internal air pressure, the balls move fast through the air and provide great bounce and spin characteristics. They ensure increased visibility on the court and come in a 1-dozen pack.