Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua’s AAO frame, the NF-A4x20 is a highly optimised, premium-quality quiet fan in size 40x20mm. The PWM version sports Noctua’s custom-designed NE-FD1 IC for fully automatic speed control via 4-pin fan headers and comes with a Low-Noise Adaptor as well as an OmniJoin Adaptor Set for easy connection to proprietary fan headers. Its superb running smoothness, reference-class SSO2 bearing and Noctua’s trusted premium quality make it an elite choice for the highest demands.