My first RBX was item #63619, a 90% polyester, 10% spandex (M) which quickly became my favorite tee. I have just ordered and received 2 shirts (M) CRM2005 style which are 100% polyester. The 2005 model's sleeves are two inches longer than the 63619 model, and the waist is also about 2 inches larger. The 2005 doesn't stretch as much as the 63619. In summary, the 2005 isn't nearly as good as the 63619. If you're a fit bodybuilder with a flat stomach and good arms, don't buy the CRM2005 unless you need a yard . work t shirt All three were made in China.