Succeeding the vastly successful NF-S12, the NF-S12B is a next generation quiet fan featuring Noctua's advanced SCD2 technology as well as a highly optimised blade geometry with Bevelled Blade Tips that improves its award-winning predecessor's airflow efficiency by up to 10%. Topped off with Noctua's time-tested SSO-Bearing, 6 years warranty and versatile 1200/900/600 rpm speed settings, the NF-S12B FLX is a premium quality fan that offers full flexibility in quiet to ultra-quiet case cooling. Thanks to its further refined blade geometry with extended leading edges and Bevelled Blade Tips, the NF-S12B achieves up to 10% more airflow and static pressure than its much acclaimed predecessor at the same noise level. Providing 1200, 900 and 600 rpm speed settings via the supplied Low-Noise and Ultra-Low-Noise Adapters, the FLX (Flexibility) version can be fine-tuned for superior airflow or maximum quietness. The latest version of Noctua?s advanced SCD drive system ensures superb running smoothness by eliminating torque variations and switching noises. Acoustical Noise & RPM - Standard: 18.1 dB(A) @ 1200RPM. With Included Low Noise Adapter: 10.6 dB(A) @ 900RPM. With Included Ultra Low Noise Adapter: 6.2 dB(A) @ 600RPM.