Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua's AAO frame, the NF-A4x10 is an award-winning, high-quality, quiet fan in a 40x10 mm size. The PWM version features Noctua's specially designed NE-FD1 IC for fully automatic speed control via 4-pin fan headers and includes a Low-Noise Adapter as well as an OmniJoin adapter set for easy connection with proprietary fan headers.