Yea I'm gonna revise my post and say a foreign part number..
Looks like they designate their kits differently for how many batteries come with the tool. Where we have to -20, -21, -22 , looks like they have a -059, -159, -259.
Probably a simplified way to keep track of sales across different counties. Advertising laws and marketing may also play a role in that, but I'm just speculating.