"on demand,what is it. the new instant hot water supplier for traveling and camping.warm water in the early cold mornings in those cold camp grounds,with a rechargable 6 volt battery,and a propane bottle for fuel.great for long trips across the country,portable enough for carring in the trunk,at any roadside camp area.refills easily at any canadian tire across canada. try it you will enjoy the comforts of a nice warm wash down on the road."