Bought this recently because I thought it was an ANK-25-101, however it is actually an ANK-2501, which is different, rarer, more interesting, and much harder to google. It has different switches, which Deskthority calls Olivetti Dome With Slider, which utilise a conductive PCB rather than a sensing membrane.

Despite being externally identical, with the same connector, and an identical SDL to D-sub cable, it appears to be incompatible with available ANK-25-101 converters.

Interestingly, despite the excellent build quality of pretty much every facet of this board, the key feel sucks. It is very short travel, and quite scratchy despite lube. Sounds good, though. Clicky rubber dome switches are wild.