Form flattering, body sculpting look (if you want it looser get a size up!). Light weight, has flat-locking seams for flexibility and strength.
Muscle Nation has added side split hems to the bottom sides to make sure no annoying roll up the body. With hip bearing styles (in light weight fabric), this tends to creep up and make you keep pulling the tee down. With their split hem design there will be no issues and also allows for that flexibility when squatting, training and moving around.