Wilson WRT1019W Practice Extra Duty Tennis Ball Case The Wilson Practice Extra Duty tennis ball is great alternative to other tennis balls for teaching and coaching. The Wilson Practice balls is an economic value and does not meet tournament standards. Instead, it is a great ball to use for teaching beginners or for practice.The Wilson Practice Extra Duty case contains 24 cans (3 balls per can- 72 balls per case).For more information on Tennis Ballsor Tennis Ball Machines, check out our Tennis Express Buyer`s Guide.The Wilson Practice Extra D! Must ship to school address or country club. Wilson Tennis Balls | Extra Duty | Durability | Outdoor Hard Court Ball Size - (See Description) | Color - (See Description) Authorized Wilson Dealer. All racquets are strung and ready for the courts! SEE SELLER DETAILS FOR RETURN POLICY.