So, I'm 5ft 2in, about 157cm tall and weigh between 110 and 135 pounds at work. elastic, almost like knit, but not quite. This is fantastic as the shirt fits my entire weight range well. She's more relaxed with less weight, yet supple enough to handle the 20-30 pounds I'm gaining. The material is a 50/50 poly-cotton blend, so take care when washing. IT WILL SHRINK WITH CONTINUOUS USING OF HOT WATER. Also, the shirts are designed to fit while maintaining a decent length. These are casual sports polo shirts, so I would not recommend tucking them in. Overall a good buy if you know what you're getting and feels comfortably thinner than most would be comfortable with, but you can always add more layers.