100% cotton cannot be beat for quality and comfort, plus, even better, there is actual substance to the weight of the fabric. It is not completely opaque, but not completely transparent like EVERY other undershirt out there in every brand. As well, the sleeves are double stitched at the shoulder! It is really almost the quality that cotton t-shirts used to be. The only, as my son would say, "cringe" factor is the Giant CK name on the front bottom of the shirt, so large it looks a bit ridiculous. I almost took a star off for that, but I am otherwise so floored by the quality that I could not do it.