Tablet / Keyboard identification?

I bought a job lot of photographic gear last week, and in among the lenses etc. was a tablet cover / keyboard, which looks to be for some sort of Windows tablet.

It isn't bluetooth, the connection is five metal pins that must touch contacts on one of the long edges of the tablet, with two lugs to locate it. The lugs are about 65mm apart, if that helps at all:



The cover folds as a support for the tablet. Does anyone have any idea what tablet it fits?