UNIQLO Heattech Ultra Stretch Slim Fit Pants (No Zipper) Denim Style Light Blue Kids' Pants 120 Amazingly stretchy and easy to move in, also incredibly warm. Easy to coordinate and versatile. Uses Heattech with heat generation and heat retention functions. - Easy to move in with highly elastic ultra-stretch material. I think there are no stains or fraying. I loved them, but my child has outgrown them, so I'm selling them.