The furnace thermal rash vest is a great way to add more warmth to your wetsuit if you feel the cold. The polypro inside the vest which is like fleece will help retain your core body temperature and keep you in the water for longer. POLYPROPELYNE UNDER GARMENTFURNACE THERMAL LININGFLATLOCK STITCH8OZ LYCRA GUSSETTHUMB LOOPMore Thermal Rash Vests, Rash Guards