The Pro Penn Marathon tennis ball has been named the official ball of the PTR (Professional Tennis Registry) since it is established as an exceptionally durable and long lasting choice for training and playing facilities. The ball offers incredible freshness and feel while playing, and it lasts much longer in comparison to standard ball thanks to the Encore™ technology expanding the durability of the core up to 22%. Furthermore, with the LongPlay® felt – the ball ensures great playing characteristics and optimal visibility on the hard courts. It is supplied in large quantity of 144 tennis balls in total.