With 54 extra micro dimples for Balanced Performance.
The new JPX-S is a soft compression edition of Mizuno’s 3 piece ball – producing a balanced performance for a wider range of swing speeds. Mizuno’s engineers discovered that a softening of the core not only improved the feel of the JPX-S at impact, but also increased initial ball speed for the majority of players.
The new JPX-S also has an additional 54 microdimples (566 in total) to combine increased launch speeds with highly efficient aerodynamics. >>More info
Source: Mizuno Press Release