The next layer is your mid-layer, an insulating layer. For this layer, you can wear anything from a sweater, a turtleneck, or an insulating shirt designed to keep you warm or comfortable without adding extra weight. Some skiers choose to wear vests, and some skiers simply choose sweatshirts as an insulating layer. Whatever you choose, make sure that what you wear will keep you warm, as this layer is essential to keep you comfortable.
Next Step: Soft Shell / Fleece Layer