The information about this product is lacking both on the packaging and in the amazon description.  The shirt is 100% cotton and tagless.  I was unsure what stay tucked meant.  It means the shirt is extra long.  I bought a small for my tween son and it is skinny and 29 inches long from top of collar to bottom hem. it may work for people with long torsos but definitely a tuck in tee for anyone else.