These are nice PWM fans, some noise around 1100 rpms based on reviews.
Individually they sell for 7.99 each. Previous Front Page Deal at this price.
Fan speed: 200–1800 RPM
Airflow: 56.3 CFM/95.65 m³/h (@ 1800 RPM)
Noise Level: 0.3 Sone (@ 1800 RPM)
You have to choose Arctic as the seller for the free shipping with Prime.