From Storm website:The international market is significantly different than the US market for several reasons. The primary reasons are differences in customs, sales, and etiquette. For example, in the United States, if a bowler does well with a particular type of ball, it’s not uncommon to find several of the same balls in a league, or even on the same ball return rack. Word of mouth travels fast where we are. International etiquette is significantly different. For example, if one bowler is doing well in a league or tournament with a particular ball, it is bad form to copy that bowler and buy the same ball. As such, if you are the bowler with the ball, you have an advantage. But if you are the bowler without the ball, you are at a disadvantage. I have experienced this firsthand in my travels all across Japan. Therefore, many of our international balls are almost identical to the standard US release with very small variations, if any. The primary differences are simply the colors, logos, and surface finishes. Otherwise, they are USBC approved with very little difference in reaction or performance compared with what is currently available in our product line.