They seem to work pretty good until the EPA catches on and starts to ban their import. They're relatively inexpensive and maybe some point I'll have to get one, as it sure would be nice to heat my truck cap with one, you can run it all night and just warm, dry air pushed into your truck cap or tent, while the dirty diesel burning part it's outside. Does require about an 1 amp of electricity an hour (12 watts) to run though though.