Hi Darren,
So much of my youth was mis-spent with batteries that I'm pretty sure on this one... the U7/SP7 are now known (by most people anyway
) as C cells, while the unsealed version of the modern AA had in my day acquired the cumbersome designation of U12/D14. To complete the list of familiar types, the D cell was the U2, while the AAA was the U16.
Nice cover, David: I may just print a few of those for a little Philips radio from about 1960 that uses the things. Not worth it for the cordless mouse
Paul