The name says it all! Hot Chillys Youth Midweight are kids' thermal bottoms made of 100% polyester Moisture Transfer Fibers to keep skin warm and dry. Softly knit in a single jersey for easy layering without added bulk. This relaxed fit under layer is comfortable to wear, making it perfect for going to school or playing outside as well as winter sports. These midweight base layer pants are available in fun prints kids will love!