C.M.O. stands for Cable Management Optimized. While upgrading the traditional case fan or CPU fan with Thermaltake DuraMax Series will dramatically increase the overall thermal efficiency, the DuraMax Series fans are also Cable Management Optimized. Cable Management Optimized fans have elongated power cables (50cm) enabling users to route the cables in optimal location to prevent airflow blockage and improve the aesthetics of the built system. - Performance 9cm case fan / CPU fan with perfect airflow to noise ratio - Elongated and sleeved power cable with ensures optimal cable management to improve thermal efficiency and aesthetic. - Dual (2) ball bearing system reduces rotational friction to improve longevity and maximum performance.