As far as the numbers go, all twincam spec windscreans are either the same or interchangable. It is not a kouki thing. The 4A-C/3A-U specs ones are different in some way, not sure how.
Some are 5mm thick, some 5.3mm. Apex ones are bronzed. Some have tint at the top. Australian ones are 5.3mm thick with the top tint.