HP41 magnetic cards

[pamphonica]

I need to test an HP82104A card-reader (just received) with my HP41CV, but have no cards. I do have a heap of the long cards for the HP75, so wondered if those would do, cut to length. They may be too narrow.

Can anyone give me reasonably accurate dimensions for the original HP41 cards?

Or perhaps does anyone in the UK/EU have a few spare cards I could buy to try?

thanks
-Jeremy