Ideal Specification: Diameter: 2.5 Inches; Bounce Height About 54in. They better bounce than pressureless balls. These practice tennis balls are almost the same as the standard ones, with excellent bounce height, and can be used as professional training balls. Package List:12 tennis balls, and comes with a reusable mesh bag with sliding drawstring cord lock closure. Take it and retrieve the balls conveniently. Durable Material: This tennis ball is made from natural rubber and durable well-bonded felt material for a consistent feel and reduced shock. Thickened materials, more durable, long service life. Multi-purpose & All Courts: Our tennis balls can be training balls, game balls, dog game balls, walker floor protection balls, chair leg noise reduction balls and more. Can be used on any court, hard or soft, clay or cement, indoor or outdoor. Ideal Sports product: 12 PCS for coaches, students, and pros alike. They're perfect for lessons and are also tennis-ball-machine compatible for solo serving sessions. It can also make dogs busy and happy. Have a good time with your pet.