Here's what other sites are saying:
The Helly Hansen Junior HH Dry long underwear bottoms are an ideal base layer for highly aerobic activities, providing dry comfort for girls on the go. Made from polypropylene, these bottoms will move moisture away and maintain a dry layer next to your skin. Polypropylene fabric is soft, lightweight, and bacteria- and fungal-resistant; plus, it retains its shape. The Helly Hansen Junior HH Dry long underwear bottoms' high elasticity allows unrestricted freedom of movement.