Direct from Noctua's website:
Following in the footsteps of the successful NF-P12, the NF-P14 is a highly optimised, premium quality 140mm fan with Vortex-Control Notches for superb quietness and outstanding aerodynamic efficiency.
Metal reinforcements, SCD2 technology and Noctua’s premium grade SSO-Bearing guarantee exceptional running smoothness and excellent long-term stability.
Using the same hole-spacing as common 120mm fans and achieving a superior airflow/noise ratio, the NF-P14 is ideal for upgrading 120mm CPU or case fans.