The NF-A14 is a premium quality quiet 140mm fan with a square frame that complies with Noctua AAO (Advanced Acoustic Optimization) standard. Its square shape and 140mm mounting holes (124.5mm spacing) make it ideal for use on water cooling radiators or as an upgrade for 140mm 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 800/650rpm 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 trusted premium quality make it an elite choice for the highest demands.