lining fabric. Small foam dots sit on the exposed inner surface of the membrane. As temperature and humidity rises the membrane expands, spreading the dots apart to reduce their insulating effect and increase the membrane's surface area, and therefore increase its moisture transfer rate (its Ret rating). Airflow is a laminate designed for footwear that uses a four layer lamination, with two outer layers, the inner of which consists of a knit spacer fabric, allowing airflow and better evaporation around the outside of the membrane. References External links SympaTex website Technical fabrics B Lab-certified corporations