For Mitsubishi

Radiator Fans are manufactured using Glass Fibre Reinforced Plastic (GRP/GRE).

Each fan produces high static air pressure which is able to focus on the direct airflow, making it more ideal for forcing air through the densely packed fins of a liquid cooling radiator.
At the same time,  place greater emphasis on having the systems run quietly in order to provide good thermal performance with a minimal impact on ambient noise