They range from 4.4 pounds to 9.9 pounds. They give a pulse, or also called a bolus, every time you breathe in. My recommendation would be to find the lightest weight POC, with the highest capability of making oxygen. Some Pulsing POC have had studies showing there effective in using them at night and during the day. Again I suggest you purchase an Oximeter for $49.00 so you can test yourself while you travel.