Rosewill Teflon Nano Bearing IP56 Dust Resistant Splash Proof 140mm PWM Cooling Fan RAWB-131456 PWM function automatically adjusts fan speeds according to the CPU temperature for efficient cooling and minimized fan noise Teflon Nano Bearing Technology TNB runs more smoothly with no friction, making the fan silent, powerful and highly durable (200,000hrs) Fan Size: 140mm Bearing Type: Teflon Nano Bearing Air Flow: 82 CFM Maximum Noise Level: 13 - 21.5 dBA