[Single Trainer: 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 Sturdy and Stable: Made of PE plastic the tennis trainer base stays in place once filled with water or sand thanks to the anti-slip strip Light and Portable: The lightweight tennis trainer is only 7.8 inches in size; after practice simply wrap the cord around the base and take it with you Indoor and Outdoor Use: It is suitable for indoor and outdoor practice such as playgrounds gardens parks tennis court and etc; the tennis trainer can significantly improve swing rhythm tempo footwork and techniques "Designed for Single Training: The tennis self trainer is equipped with elastic ball with 13 ft elastic string; when you hit the ball the tennis ball will rebound again by the traction line to achieve the effect of repeated strikes; so you dont need a training object to meet your daily training needs"]