Unless for some reason your vendor (Lenovo) has decided to stick a second M.2 slot in your laptop model and you can just buy an expansion drive in a couple of years when they're cheaper without having to swap out your old one. That was one of the nicer surprises about the ThinkPad X1 Extreme Gen 2. I'm guessing you can get a configuration that uses both slots from the start, but I didn't see it when I bought mine.