How is an electrical jumper made? What are the materials used and how is it assembled?

I don't exactly know how this gadget is referred to but this "electrical jumper" is being used in order to save electricity consumption if you have too may appliances at home. I know I'm causing confusion here because jumpers are generally used in computers or as electronic testers but it is also used as power savers. Maybe I'm just using the wrong name for it. Could anybody please help me to learn how to do it? Help! Anyone?