Neoprene layers can be worn with other dry layers, or on their own. Sailing wetsuits are typically 3-5mm and come in a range of cuts. Most are reinforced at the knees and allow good flexibility. Tops made from similar fabrics can be work to add additional warmth on cold days. It is not uncommon to wear a wetsuit as a first layer with a set of spray gear on top to help cut wind chill on cold days.