The Astrox 99 is stiffer and has a greater head weight. In short, it's a proper sledgehammer. In fact, Kento Momota went from the 3U version to the 4U version midway through the 2019 season because he said he felt tired and sluggish in his matches.
I had previously tried the original orange version Astrox 99 and I tried very hard to like it but couldn't. I tried this newer version and I still don't like playing with it. As someone who isn't physically very powerful, I felt I wasn't able to maximise the potential of the Astrox 99. Even with the added stiffness and head weight, I didn't feel that my smashes were any harder or faster compared to, say, the Astrox 88 Pros.
In terms of net shots and lifts, this thing is extremely accurate and I believe this comes from its added head weight. I can see why the Astrox 99 is favoured as a singles racket (I don't remember seeing any top-end doubles players on the world circuit playing with the Astrox 99, the Astrox 88 and the Astrox 100ZZ appears to be a more popular choice amongst doubles players).
I cannot wait to see the latest generation of the Astrox 99. If its design philosophy goes in the direction of the Astrox 88, including a fully recessed frame profile and a more responsive racket in terms of playability, this is going to be one hell of a racket for a lot of players.
If I were to compare the Astrox 77, Astrox 99 and Astrox 100ZZ, in terms of head heaviness, the Astrox 77 is the lightest, followed by the Astrox 100ZZ, then comes the sledgehammer Astrox 99. For stiffness, the Astrox 77 is the most pliable, followed by the Astrox 100ZZ (which is really responsive and good to play with), finally the Astrox 99 with incredible stiffness. In terms of speed, I would put the Astrox 99 as the slowest racket, then the Astrox 77 before ending with the Astrox 100ZZ, which is very impressive considering the amount of head weight and power you have access to with it. For a more detailed comparison of the physical dimensions of the Astrox 77, Astrox 99 and Astrox 100ZZ, check out the table and also my YouTube video below!
What do you think about the Astrox 99? Drop me a comment and let me know!