I've used Dunlop Grand Prix Extra Duty Balls for a couple of decades. I started using them at USTA tournaments after noticing their performance and durability. I've been impressed by how consistent the performance is can after can. I did pull the string the last purchase and bought a full case, all good so far. I'd compare these to other brands as superior in general, but am impressed with the consistent quality. I was buying in packs of 4 from a large general retailer, running into flat, non-performing balls.

The balls keep pressure well and bounce great even after 4 hours of hard hitting.

The Dunlop Grand Prix Extra Duty tennis balls seem to last longer than the Extra Duty Penn balls.

Big fan of these balls. They hold their bounce, have a good weight and last nearly 3 sets. I went on a mission to find the best cost effective ball and this one takes it by far. Much better than the Penn and only $5 more than the other Dunlop for a case makes these well worth it. Much better better felt on the Grand Prix. If you want the best ball and want to spend less than $120, get these.

I think Dunlop Grand Prix Extra Duty Tennis Balls are the best for playing and lasting. Tennis point did a good job delivering them in a timely way.