Re: American Professional CL 15504
That is a Martin (beveled tone holes)
C melody (C)
In Low pitch, a=440 (L)
It is an early version, prior to 1930.
This would be considered a Stencil.
Someone paid Martin to have the name American Professional put onto the bell, therefore the name Martin does not appear.
Possibly the low C key guard has been replaced by a Conn key guard at one point.
The Mercedes emblem key guard at the bow was used on Conn, but I have not seen it on a Martin. Does it appear to have been resoldered on at some point?
So, it is in the key of C, so you can play the same guitar music and it will be in key.
Not much value. Maybe 200 bucks. I assume you also have the neck to it.