Seems to be a track used jersey. Has a several marks and stains from use, which give it a nice worn patina. The stains should be removable with treatment and laundering. Be sure the measurements work for you before you purchase! For best fit, compare my measurements to your favorite shirt. See pics for condition and measurements below:

Chest (Pit to Pit) - 21 inches

Shoulder to shoulder - 17 inches

Length (Collar Seam to Bottom Seam) - 31 inches 

Reasonable offers are always accepted!