The NF-A14 is a premium quality quiet 140 mm fan with a square frame that complies with Noctua's AAO (Advanced Acoustic Optimization) standard. Its square shape and 140 mm mounting holes make it ideal for use on water-cooling radiators or as an upgrade for 140 mm case fans. Featuring sophisticated aerodynamic design measures such as flow acceleration channels, the NF-A14 further improves the renowned quiet cooling performance of the award-winning NF-P14. The ULN version provides super-slow 800/650 rpm speed settings for ultra-low-noise applications and highly noise sensitive users who demand near-silent operation. Its superb running smoothness, reference-class SSO2 bearing and Noctua's trusted premium quality make it an elite choice for the highest demands.