Penn Tour tennis balls are high performance tennis balls featuring Penn’s exclusive LongPlay® felt for extended wear, and feature our Smart Optik® high visibility felt treatment which makes it 19% more visible than a standard tennis ball. Penn’s premium line of balls are the most technologically advanced tennis balls in the world, providing players with optimum core and felt technologies for the perfect balance of consistency, longevity, and overall playability. Extra Duty felt is for hard court surfaces. Penn Tour tennis balls are USTA and ITF approved.