I bought one previously. I can't ever tell if it's working. It certainly seems to be USELESS.
Woot didn't respond to an inquiry.
The mfr, when I called, had very nice people answering the phone, who gave lots of different answers...it has a fan, it doesn't have a fan, just wait 10 minutes.
It seems to have a heater in it that does get warm, but, no fan. No sense that the heat is leaving the device. It either isn't working, or just sucks.