XCM 360 core cooler (add on fan) can be used with XCM High Speed air cooler (more efficiency and powerful) or independently, unlike another brand of external fan,external Xbox 360 fan can only cool the temperature of the Xbox 360's outer surface but does not cool the temperature of the CPU/GPU; therefore, making them useless to combat CPU/GPU overheating.  XCM 360 core cooler directly cools down the temperature from the core (CPU and GPU) of 360 console.