I don't mind a hard one. I hope you don't either.
I was cleaning the inside of our stick vacuum cleaner and I needed a brush to get where my fingers couldn't. I know, this old brush will do the trick, and it did. I thought about the brush.
The brush was made in Japan some 55 years ago and accompanied by a soft camel hair brush with hairs about 2cm long and 4cm handle. That the plastic hasn't disintegrated nor the bristles fallen out is amazing. While a little discoloured, it is truly amazing that it works as well as it did when new.
So, what was the purpose of the brush and the second one for that matter? I now use the second one for cleaning my electric razor. You do have to be of a certain age.
Clue at 16.00 if no one has the answer by then.
Later edit: Cro of Magnon's Meanderings correctly suggested it is a brush for cleaning typewriter striking parts that hit the inked ribbon and print onto the paper. I suppose they used to get a build up of gunk from the type writer ribbon plus some dust. Oh yes, if you are late to this post, do comment if you knew what it was, hey Grace.