Brand New Design-Unscrew the cap on the training base so you can fill with water or sand. Once it's filled, it will be heavy enough to hold your swing. The anti-skid material at the bottom will holds the training base in place. There is anti entanglement design on the top of the base, so you dont have to deal with entangled rubber string. Solo Tennis Training-Single player training tennis: no need to wait for a companion, simply training with yourself. No need to pick up the ball, the tennis ball hits out with the elastic rope to rebound automatically. Get started to train your serve, forehand and backhand easily. Light and Portable-Tennis trainer was made of light and durable material. You can carry the trainer wherever you want with the mesh bag. When you are done with your training, simply wrap the rubber string around the tennis trainer, place it in the mesh bag and you are ready to go. Suitable for - tennis trainer is a good gift for tennis lovers, family and children who like to play tennis. It can significantly improve swing rhythm, tempo, footwork and techniques. It is ideal for indoor and outdoor practice such as playgrounds, gardens, parks, tennis court and etc