Mr. Heater Portable Buddy Heaters work very well in tents and are used all over the upper Midwest for ice fishing in enclosed tents/shacks and they work very well. As has already been said, they do include safety devices built into them. This is directly from their website: "With the Oxygen Depletion Sensor (ODS) and accidental tip-over safety shut-off you can be sure that you will enjoy years of comfortable indoor safe heat." I have used one for 10 years while ice fishing and also used it in one of our first pop ups. Follow the directions provided and you will be safe and warm.