Xigmatek Computer Case Cooling Fan XAF-F1451 Copper bushing axis Bearing to provide long-term life and stability. Waveform and enhanced lubricant circuits to provide outstanding aerodynamic efficiency Wave Shaped and small hub dimension generate extra high airflow. Round frame of 140mm fan able to be installed on 120mm or 140mm mounting holes Wide range of PWM function (800 to 1300 RPM) to simply and easily adjusting fan speed with the latest ETC IC. Wave Blade technology