a radiant heater for propane tank.The kind you use for a gas grill..I have that type of heater with two radiant grills that are seperatly adjustable..It just screws right on top of the bottle and has an ignitor as well.I think I paid about a hundred bucks for it and costs about 10 bucks to fill it..I have a 2 car garage and it would bake me right out of there if I left it going full blast..Hope I helped..