Extention cords are classified by pins, blades, socket shapes, and co-operating parts together, according to the inventors Michael O'Keefe and Theodore Sares. Extension cords have been used for many years to lengthen the cord of an electrical device so that it can be connected to a power supply or receptacle. One end of the extension cord is formed with a socket or receptacle that is sized to engage with a plug located on the cord of the electrical device while the other end of the extension cord is formed with a plug which is adapted to engage with a socket located at the power supply.
