From the description:
Quiet: The customized heat sinks mounted to the hash boards, one box over S3 to control the air flow, two fans mounted on both front and back ends that mean fans are able to work at lower speed to dissipate all heat easily. This design let S3 run at much lower noise level.
Yep thats what it says, but on their website they posted the screenshot showing both fans running at 2850rpm. That isn't quiet from my experience.