BigDiesle is right, the Espar is good. I have a TriPack with it and last winter I was up in Idaho. Jumped outa the truck and jumped right back in, way to cold for this Florida boy :sad: Turned up the heat and went into eat. When I came back out you couldn't stand it in the sleeper it was so hot, had to leave the door open and open the back door for awhile till you could get to breath.