Very silent
This fan is ridiculously quiet. It is so quiet I HAD to put a small mark on the visible rotating center section for a visual reference that it was actually running. Even with my ear next to it, I could not hear it running. I am very happy with this fan. I use it as the layer cooling fan on my Tevo Tarantula 3D Printer. I will recommend it to everyone who asks. Thank you for making such a great fan.