Feature:1. There is a valve on the base to put sand or water to increase the weight, and there is a small on the side for hanging the strap.2. Easy to use and convenient, no need to pick up the ball, light weight and easy to carry, very suitable for single practice.3. It can improve your concentration, exercise ability, hand and eye coordination, and develop interest in sports.4. The semi‑circular ball slot structure makes the ball easy to attach, and the wall‑mounted traction rope slot design is helpful for cleaning.5. It can be used with ball with a rope, use elastic rope to tie the ball to the base for precise control and practice tennis skills.Specification:Item Type: Tennis Ball BaseMaterial: ABSColor: GreenSize: Approx. 21x14.5x5cm/8.3x5.7x2.0inWeight: Approx. 90.0g/3.2ozThe base can be filled with water or sand Package List:1 x Tennis Ball BaseNote:Can be used with rope tennis (this product is only a base, without rope tennis).