A is for driver side and B for passenger side. Might work, just try them out and make sure the integrated airfoil is the right way. Or change your order if not too late.

One side note is that 424A and 422B is what Bosch calls for in their book. However, you will notice that the tip of the passenger one is "hanging" off the windshield a bit. No big deal really but I went back to my local auto parts store and exchanged the 422B for the 421B a lot folks here run. Not much difference in length, but enough to not "hang" anymore. There is no performance difference, simply a cosmetic one.

About the performance, so far I am not that impressed. They leave streaks on the windshield, both driver and passenger. Before being totally disappointed, I will "lube" the hinges and springs so that a little more downforce is applied and also wipe them with alcohol to get rid of possible crud on them. We'll see if they work better.