Features:1. The base is made of quality plastic, sturdy, the bonus rubber rope is highly elastic and wearable.2. The base has a valve for putting sand or water into it to increase the weight so as to provide stable support for training.3. The small ring on the side is for hanging band, and the concave part for placing tennis ball.4. Easy to use and convenient for training without picking ball, lightweight and portable, suitable for many places like garden, park, etc. 5. Great accessory for tennis training, can help to perfect skills of tennis.Specification:Material: Plastic + RubberColor: BlueBase Size: approx.15 * 20 * 5 cm / 5.9 * 7.87 * 1.96 inchBall Seat Size (Dia): approx. 6.3 cm / 2.48 inchElastic Force of Ball: approx. 1.2 m / 3.39 ftElastic Force of Bandage: 4 - 8 m / 13.12 - 26.24 ftWeight: approx. 270 gPackage List:1 x Tennis Trainer Base 1 x Ball with RopeNote:Stopper style is shipped randomly and make sure you will not mind before ordering..