Bought these for my 9 year old son who has never worn t-shirts until this winter.  He says they are very comfortable and, while thin, are warm under a shirt or as a pajama top.  He did not have the issue others had with them running small, he likes them snug and they are long enough  to tuck into his pants.  He is fairly tall for his age (54") and weighs 80 lbs and he fits well in slim jeans. Shipping was fast and packaged well with no problems.  I am buying more since he really likes them.