The hat is marked as a size 7-1/8 US (7-3/4" x 6-1/2" interior from inside of sweatband reed).  

The hat has a 3" brim (measured on the underside of the brim from the sweatband reed to the brim edge).  The brim has a raw edge.  The crown is 5" open with a 3/16" grosgrain ribbon and "knot". 

The felt has no major staining or visible moth nips, but does have some light soiling and a few dark spots.  The thin ribbon is free of stains, but have some loose threads at the ends.  The leather sweatband is in good shape, fairly supple and the debossings still shine, but there is a wrinkle and some verdigris at the ferule.  The embroiderd "Last Drop From His Stetson" liner is nice, but the plastic liner tip is cracked and the liner body shows a little staining or foxing.

The felt has a nice hand and shapes easily.  

I'm basing the date estimate on the model, fonts used, logo style, embroidered liner, the plastic liner tip, style/color of the factory size tag and the color, width and construction of the sweatband.