Tennis/Cricket trainer rebound ball kit is made of durable and high-quality high-density PE plastic. Includes 1 string tennis trainer rebound balls and 1 trainer base .No need for a partner or ball machine. When you hit the ball, the tennis ball will rebound again by the traction line to achieve the effect of repeated strikes. Get started to train your serve, forehand and backhand easily. The top is a semi-circular groove design, tennis balls can be placed when not in use. The middle part is designed as an annular groove, so you don't have to deal with entangled rubber string. The anti-skid material at the bottom will holds the training base in place.