I bought my strop second hand and am a bit confused by it.

It's a Suntorbach 2"x14" two-sided strop. Rather small with black leather.

I am trying to figure out
A: what the number 2250 on it means. Is this simply a serial # stamped on by the company, or does it have meaning for the stropper?

B: The back side of the strop is leather, but this side appears to be hardly used and has a weird square grid pattern that looks pressed on. Does anyone know what this is?