Zalman outs a new fan, the the ZM-SF3 with  "Shark's Fin Blade" design to reduce noise and increase airflow. The fan measures 120 x 120 x 26.4 mm, weighing 118 g.Other noise-reducing features include the "Everlasting Quiet" (ELQ) bearing that has a lifespan of over 150,000 hours, silicon blocks at the corners of the fan to dampen vibration, as well as silicon pins instead of screws to further reduce vibrational noise.

Apparantly the fan's frame uses tiny segments of silicone to dampen vibration, and silicone pins are provided instead of metal screws that bring down vibration transfer to the chassis even further. This results in a rated noise level of under 25 dBA. 

Fan RPM is 900 ~1,500 rpm.