Premium quiet fan, 40x40x10 mm, 12V, 4-pin PWM, max. 5000 RPM, max. 19.6 dB(A), >150,000 h MTTF Award-winning A-series design with Flow Acceleration Channels and Advanced Acoustic Optimisation frame for superior quiet cooling performance 40x10mm size ideal for 1U servers or replacing fans in network and storage equipment (routers, switches, NAS etc.) or other devices such as DVRs 4-pin PWM version for automatic speed control via 4-pin PWM fan headers, broad 1000-5000rpm speed range (3700rpm max. with supplied Low-Noise Adaptor) Includes anti-vibration mounts, fan screws, Low-Noise Adaptor, extension cable and OmniJoin adaptor set for connecting the fan to proprietary fan headers