The NF-S12A features the third evolution of Noctua"s classic Straight Blade Design that has earned its S12 series countless recommendations from hardware journalists and enthusiasts around the world. * The NF-S12A"s Anti-Stall Knobs reduce flow separation phenomena in medium to high impedance situations n thereby increase the fan"s stall margin, that is even more versatile than its renowned predecessor . * Noctua"s AAO (Advanced Acoustic Optimization) frames feature integrated anti-vibration pads as well as Noctua"s proprietary Stepped Inlet Design and Inner Surface Microstructures, both of which further refine the fan"s performance/noise efficiency. * Noctua"s Stepped Inlet Design adds turbulence to the influx to facilitate the transition for laminar flow to turbulent flow, that reduces tonal intake noise, improves flow attachment, incur suction capacity, especially in space restricted environments. * Integrated Anti-Vibration Pads made from extra-soft silicone minimize the transmission of minute vibrations while maintaining full compatibility with all standard screws and other mounting systems. * Providing 800 and 600 rpm speed settings via the supplied adapter, the ULN (Ultra-Low-Noise) version is tailor made for serious silent enthusiasts who demand super-slow running speeds and utmost quietness of operation. * The fan"s short 20cm primary cable minimizes cable clutter in typical applications while the supplied 30cm extension provides extended reach when necessary. Both cables are fully sleeved. * The latest version of Noctua"s advanced Smooth Commutation Drive system ensures superb running smoothness by eliminating torque variations and switching noises. This makes the NF-S12A remarkably quiet even at very close distance.