The Penn Championship Titanium tennis balls are an incredibly durable choice for demanding players that preserves the characteristics and fresh feel for longer due to increased core pressure retention within a natural rubber core. Additionally, the balls additional longevity and enhanced visibility is ensured by a thicker grade of the felt. These USTA approved (United States Tennis Association) tennis balls guarantee a phenomenal feel as well as excellent playability through consistent specs and it is supplied as one dozen (12 tennis balls in total).