Before there was in-car navigation, there was The Motorist’s Memory by Faber-Castell: a small notepad tucked into a vinyl holder which had a strip of adhesive tape on the back. It’s equal parts high-tech and dowdy™.
It also comes with a pocket pencil, a Castell 9000, but with the marking “M”.
I have yet to see a Castell lead pencil with this marking outside of its use here (see update at the end). I’d say it has a lead near to a 3B (these would be fantastic with the green plastic Perfect Pencil):
I’m not sure of the date for this item; I’m guessing somewhere between 1950 and the 1960s.
I wonder if, in some forgotten corner of a warehouse, there are boxes and boxes of replacement pencils and spare refill pads.
NB: I should note that I apply this “forgotten-box-in-the-corner-of-a-warehouse” fantasy to every single discontinued Faber-made item that I like.