These are Comfort Color (thicker material and typically more of a lifestyle shirt than a workout shirt)
 
6.1 oz./yd² (US), 10 oz/L yd (CA), 100% ring-spun cotton, 30 singles
Garment-dyed for that lived in feel and almost no shrinkage at home.
Soft ring-spun cotton fabric with 100% cotton threads
Relaxed fit
Topstitched, classic width, rib collar
Shoulder to shoulder twill tape
Signature twill label
Made With Respect Proud member of the U.S. Cotton Trust Protocol
Made with OEKO-TEX certified low-impact dyes
Our clean pigment dye colors are salt free