Kaia Gerber and Hailey Bieber wore the must-have cozy piece for cold weather, and you're going to want to add it to your wardrobe, ASAP. The models have been spotted in the popular Free People Hit the Slopes Fleece for their casual, off-duty looks. Gerber wore the zip-up jacket version in the navy blue shade with a gray tee, black leggings and slip-on sandals.