***** **********Best Quality Guranteed. *****Premium quiet fan, 40x40x20 mm, 12V, 4-pin PWM, max. 5000 RPM, max. 14.9 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*****40x20mm 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, 5000rpm maximum speed (4400rpm with supplied Low-Noise Adaptor)*****Includes anti-vibration mounts, fan screws, extension cable and OmniJoin adaptor set for connecting the fan to proprietary fan headers