I use three dispensers in my house, and they really help my two cats get along. I noticed recently that two of the three (and they are the oldest, over a year probably) not only got very hot, but both have melted plastic and a scorched area, behind where the wick comes up! My boxes didn't have the warning to replace every six months. The newer one I use hasn't done that, but - wow, I think I'll try the Glade idea with one, and see how it works out. This is a good thing to warn people about!