The USAPA approved X-Performance 40 Pickleball-X balls are one of the finest balls ever created for the sport of pickleball. Using only the best PE material and theadvanced single piece design, this ball will withstand hours of the most aggressive play. The X-Performance 40 balls deliver a superb flight path thanks to the precision of themachine drilled holes. Perfectly weighted and sized, these balls will certainly impress anyone on the court! The X-40 is now the Official Ball of the US Open Pickleball Championships!