... etc.1.Performance: low noise, light vibration,strong cooling, muti-role, long life and environmental protection. 2 ... the fans ,not base on the speed, when the cooling efficiency are same, we choose the ... flow reach the cooling demand,we choose the fans with lower speed, Cause lower speed,longer life span. ... RD signal (Stall warning), FG signal(Detect fan speed value), water proof and so on.4.CEETIFICATE ...