C Skins HDI Polypro Mens Short Sleeve Thermal Rash Vest The C Skins HDI Polypro thermal rash vest is designed to keep you warm on the coldest of winter days. It can be worn under a wetsuit as an extra barrier to retain body heat for longer or on its own in warmer climates. The thermal material acts in the same way as thermal underwear but is designed to be worn in the water. FEATURES Breathable flatlock seams High Lycra collar Heavyweight Poly Pro lining