This is the best blend of cotton and polyester for undershirts.  They feel great when you wear them all day and they have a little bit of give for movement, unlike 100% cotton.  I believe that they also do not shrink like cotton shirts as well.  These are the only blend of fabrics that I wear for undershirts.  I also look for this blend in my everyday T-shirts.  I would recommend the product to anyone that wants to be comfortable.