Though they are calling these thermal underwear, they are more like pajamas to me.  But certainly they would be worn under other clothing for layering.  The top is a little bit different in color.  The light-colored streaks are actually red/orange.  The overall top is a bit darker.  I was going to try and take a picture to post, but even with my camera it turns the red/orange streaks into a yellowish color, as it shows in the pictures.

Both the top and the pants are made of 100% polyester.  They are Made in El Salvador.  They are very lightweight.  They have a very open weave for air to pass (another reason I don't think these are actually thermal underwear.  There is some stretch to the fabric.