So, if you're a coach looking for balls that last longer and don't 'lose' themselves, Tretorn Micro X Trainer balls are definitely for you.
•Neither pressurized nor permanent pressure™, Tretorn’s micro cellular technology is patented worldwide and recognized by the International Tennis Federation as the pioneer of a new category of tennis ball. The result: a highly playable ball that does not lose performance over time.
•A conventional pressurized ball flattens on the strings as it is hit and resistance is provided by the compressed air within the ball. A small amount of air escapes each time the ball is struck, reducing air pressure. With this new category of ball, 700 million air-filled micro cells take the place of compressed air. These cells cannot escape through the ball‘s rubber core, resulting in a ball that never loses its bounce.