Effectively prevent the formation between the "24V DC Cooling Fan" fan box end and narrow; in fact, each vendor has its own fan blade design methods, each design; oil bearing; oil bearing sleeve is sliding friction bearings, the use of lubricants as; ball bearing; oil bearing due to the short life cycle, bearing the internal control directly affect oil; "24V DC Cooling Fan" single ball bearing; single ball is the traditional seal bearing improvements; double ball bearing ; double ball bearings are more upscale; the bearing of the working environment is relatively stable; "24V DC Cooling Fan" blessing bearing; blessing bearing kind of design, effectively preventing the formation between the fan and the fan frame narrow end airflow disturbance zone and air turbulence generated by wind noise.