These Slam Balls are designed to be thrown again, again & again. The ball is made from a high quality flexible PVC & is filled with s&. The materials used are rubber & s&, this should allow the ball to fall ball firmly on the ground & not to bounce. The thick rubber layer on the slam the balls will make the ball extra tough. This allows the Tunturi Slam Balls to last longer. In addition, the rubber coating will protect the floor on which the training is taking place from damage. The slam ball is available in different weights; 5kg, 10kg, 15kg & 20kg.