Horstmann button help with date please

I thought this would be easy enough to figure out....but not for me
I've been here
http://relicman.com/buttons/zbackmarkhorstmann.html

and many other sites, but just can't find this exact mark. I see many with Philada, Philadelphia, and Horstmann & sons, etc., but none with just Horstmann and Phil a. Can you help? It's probably one of the cheap ones, but that's ok, would just like to know.
I drew a picture because it's sort of hard to see on the button.Thanks for your time.

 

Maybe you could write to the person who runs that site? http://relicman.com/

 

Thank you fig That's a great idea, I'll do that.