Pro Penn Marathon - Tennis Ball 4 Pack Felt:Extra Duty The customizable vibraton dampener used

The customizable vibraton dampener used by Rafael Nadal

Fabric: 91% Nylon/9% Lycra

Fit: Length is true to size

Gauge: 16 (127)

Balls are 75% slower than normal tennis balls

Pro Penn Marathon - Tennis Ball 4 Pack Felt:Extra Duty The customizable vibraton dampener usedPro Penn Marathon is Penns longest lasting tennis ball featuring exclusive Encore Technology for a 22% longer lasting core and high tenacity LongPlay Felt for extended play. Pro Penn Marathon is the official ball of PTR because of its guaranteed longevity, durability and visibility. Pro Penn Marathon is available in Extra Duty Felt (for hard courts), Regular Duty Felt (for soft courts) and Extra Duty High Altitude (for higher altitudes). Penns