It is shiney so it can reflect the heat to one area
ProFusion Heaters are made in China and is sold by Northern Tools and Equipment.
Tubular heaters are not specifically made for the purpose of heating oil. There are tubular heaters that use oil as a means of heating but they are not made to heat oil.
GE hot water heaters are made by Rheem.
California
California
yes
Yes they were made in Dayton, Tennessee
Heaters can be made out of various metals such as stainless steel, aluminum, or ceramic materials. The choice of metal often depends on the type of heater and its intended use.
There are actually specially-made heaters for areas like garages and warehouses. Here's an example: http://www.lennox.com/products/garage-heaters/
The most energy efficient pool heaters are solar heaters. You can find solar pool heaters made by Vortex, SunHeater and EcoSun amnong other companies. For non-solar powered you will want to check out pool heaters by Hayward and Pentair.
If you are referring to RUUD, they are now mostly made in Mexico.
Solar heaters are useful for heating water with natural energy, thus saving electricity. The question is can effective solar heaters be made for less cost than using the electricity.