Very very quiet, with this small and delicate device surprisingly high air capacity. Excellent for forced cooling of electronic devices in tightly enclosed space. Set have three pieces in series via the vent hole of my active subwoofer (in the narrow space was a little warm) - now hold the power unit absolutely cool. Need tatsächlich12V to run. However, do not be turned down because of their minimal noise level. Work with any arbitrary mini-DC power supply, as very low power consumption.
