A 12 inch cooling fan is a type of cooling device commonly used in computer mainframes and other electronic devices. The size of the fan refers to the diameter of the fan impeller. a 12‘ fan is approximately 30cm in diameter, which is equivalent to two 14’ or 12’ fans side by side. In general, the larger the fan size, the more air flow it can transfer and the better the cooling effect. However, the choice of fan size also needs to take into account the limitations of the internal space of the device. In addition, the fan's rotational speed, number of blades, impeller shape and material will also affect its cooling effect.