We have larger, very quite C-pap's and kind of heavy machines for home. You can not hear them run. Only the person breathing. And we picked up smaller ones we can run on 120 or 12 volt for travel. They are not so quite. The company we deal with is a local company and they sell new, rent ect. The machines show the hours used. We picked up used, small not to quite units with very low hours for a couple hundred cash. They are small, light and have no water chambers. Just the thing for travel.