egg incubator accessories（egg incubator circle fan with heater） is composed by air inlets , air outlets, and Circle fan.
According to the position , it can be called side fan, top fan, back fan and middle fan.
Usually the circle fan are runing from the beginning to the end.
And this type of cirelce fan is usually as top fan, side fan.
The usage usually is even the temperaure in the incubator.