Here's what other sites are saying:
Find her happy medium when you layer your girl with the lightweight Icebreaker Girls' BodyFit 200 Mondo Zip-Top for a day out on the slopes. For days with temps hovering around freezing, this merino wool top is just thick enough to keep her body heat circulating, but not so thick that she sweats and freezes on the chairlift. Icebreaker's natural wool fiber insulates her core when she's cold, breathes when she's hot, and wicks her sweat away as she does her thing on the mountain. The high collar features a 1/4-length zipper for venting and easy on and off, as well as flatlock seams and plenty of room in the sides for a comfortable fit no matter what she uses to get from the top of the hill to the bottom.
Icebreaker Kid's Mondo Zip 9-12 Years DECENT FEATURES of the Icebreaker Kids' Mondo Zip 9-12 Years Base layer for cold play Lightweight, warm merino breathes to prevent overheating Raglan sleeves/side gussets for moving comfort Close to body fit Flatlock seams to prevent chafing