A custom impeller is a type of fan that is designed and manufactured to replace and meet specific requirements for a particular application. Custom impellers can be made from various materials, such as plastic, metal, or composite materials, and can have different shapes, sizes, and features. They are commonly used in industrial or commercial applications where standard impellers are not suitable and can be created in accordance with OEM requirements. The design and manufacturing of custom impellers typically involve advanced computer-aided design software, precision machining or casting techniques, and rigorous testing and quality control procedures to ensure optimal performance and reliability.