Pressureless balls are opposite to pressured, they play better the older they get. They start out harder and go through a court faster but become closer to a new ball with age. The Treton are good for consistent bounce, I have some no-brand that play well but the seam where they join is a touch thicker than elsewhere and can result in uneven bounce, I prefer this as it means the ball machine is not too consistent, and it's only a slight variation in movement. Mine are all about 1 year old and going good.