Noctua NF-A14x25 G2 PWM Sx2-PP chromax.black 1500RPM 140mm Next Gen Fan Set\n\n[features] Succeeding the iconic NF-A14; the NF-A14x25 G2 has quickly established itself as a new benchmark for premium quality quiet 140x25mm fans. Its advanced aerodynamic engineering featuring a novel Progressive Bend impeller design with Centrifugal Turbulator hub; winglets and a record tight tip clearance of only 0.7mm enables the G2 model to provide a significant boost in performance-to-noise efficiency over its renowned predecessor. The Sx2-PP set contains two fans that are slightly offset in speed (+/- \n25rpm) in order to avoid undesirable harmonic phenomena such as beat frequencies; which can be heard as intermittent vibrations or periodic humming due to interference. This makes it ideal for both push-pull applications and situations where two or more fans are running side by side such as in typical case fan configurations as well as on 280 or 420mm water cooling radiators. Topped off with Noctua;