We use them for people who need them for Aspirators or such like, people who suffer from Asthma. There are certain types of aspirators that are the only approved type for use on a/c, you can't just plug your home one in for obvious reasons as stated above.. .Things have to be approved by the reulatory bodies you can't just go around plugging things in. <img border="0" title="" alt="[Eek!]" src="eek.gif" />