it is a tankless water heater, fueled by propane, and powered by two D batteries.
I had a similar one in my house in ME, it used 110V power but drew less than 2 amps, it was made by (Rheem). Some of them are able to be powered by 12 V or even don't use any power, the water flowing through them generates the power needed to operate.
If you look at many off road camping, jeep, or 4 wheel drive sites you will see many people have a 12V water pump being powered by the TV engine or battery and one of these water heaters to allow showering in the middle of no where.
Probabley a better set up than my Zodi
http://www.walmart.com/ip/4698021?wmlsp ... 90&veh=sem that I got on clearance a few years ago.