The suspicious thing is that the "20 million" strokes rating. Aren't Model Ms rated at 50M or more?
I would ask the seller to pull a key and take a picture. That would tell all.
IBM never really emphasized the lifespan of the Model Ms or any buckling spring keyboards to my knowledge.
That's a bog-standard IBM-case-clone which was pretty common for
many years. And no need for pictures.
That is a KeyTronic example with pretty good rubber domes. KeyTronic is the only manufacturer to ever use that "MADE IN USA" in the mold, and LR65976 is their old CSA number.