Comparable to the Wilson US open balls but much cheaper. I'd buying 12 cans at a time, and it preserve well. Great durability for hitting/rallying up to 1 hour when regular Penn balls from Costco is only good for less than 30mins.
My friends like to play with already used balls. These last the longest for me.
I bought these for years and would play with nothing else......until the last case, maybe from 2011, where the quality went WAY down. Many of the balls were flat right out of the can, which was never the case before. In my experience this is a formerly top notch, very long lasting and very controllable ball (although heavier than most others,) gone to the dogs. And given that I've read the same thing from a majority of formerly happy reviewers on another major tennis website, continuing up through 2014, I'm a bit suspicious of the two 5 star reviews here. (3.5 player)
When I organized our group, we played with new balls every week. The new organizer wants to play with the same balls several times, so now it really matters to me that we play with these durable Dunlop balls.