I have used Micro X balls for drills and a Playmate machine. They do not ever go dead. Eventually the ball machine balls lose their fuzz and still bounce years later.

They are the best for a ball machine. I've been using them for years. They beat out Penn by far in terms of how well they resemble a real tennis ball when hitting them and they are long lasting too.

Holabird shipped them out quickly and I was loading them into the hopper in no time.

I often use the ball machine when teaching beginner to intermediate athletes. Having tested many brands, like other teachers/coaches, I found that the Tretorn MicroX pressure-less ball holds up longer than almost any other. It maintains good bounce and the felt holds up quite nicely (longer lasting). A couple negatives: they cost more than most balls and the supply is often low. The weight and performance is close enough to your standard competition tennis ball for teaching purposes.

Holabird Sports is quick to respond with any product. I highly recommend them for your tennis needs.

Despite the high cost, these balls are the best for use with a ball machine. I first used Tretorn balls when learning to play as a child 60 years ago, and used a single box for one entire Summer. The current balls continue the legacy of quality.

Had to wait for backorder of these balls but was notified as soon as they were available. Good experience both with the balls and this company.