Just a little snapshot, but it seems to me just right at this scale--like a whisper of a message from on far, reminding one to "keep to right." (Which I'll take as meaning right as in good, not as in to THE Right!) Looks like a homemade sign to me, with the lettering hand-cut from metal - and in fact it looks a bit like a dustpan turned on end to me!
2 1/2" x 1 5/8" and in very good condition, c. 1930s-40s I believe.