Originally Posted by cluckcluck
It's still different, I can't seem to wrap my head around why it's allowed.
Are you talking about the ball differences? Why should it not be allowed? As I indicated, the balls used by the WTA and the ATP must all meet ITF requirements. The ITF specs
(see link in my previous post) are fairly narrow
in range for the 4 ball types shown. These specs include weight, size, rebound height (percentage), forward deformation, return deformation and ball color. It the balls meet the fairly tight ITF requirements, they are legal.
I believe that the slight differences between the men's ball and the women's ball is more of an attempt to slow down the men's game rather than artificially boost the women's game. Many of us still recall how boring the men's game was on faster surfaces in the early/mid 90s. Very few rallies -- it was all about a big serve and a big return. The women's game was often considered much more entertaining for part of the 80s and 90s than the no-rally men's game. The larger type 3 ball was introduced as a failed attempt to slow down the prom men's game. With that as a widely unpopular solution, pro balls were made brighter and courts were slowed down.
Here is a picture that shows the slight difference in size between the extra duty ball (on the left) and the regular duty ball: