Made of thin, fragile plastic. The photo shows brass contacts, but the contacts are steel with a thin coating of zinc. It rusts easily, unlike higher quality connectors that use brass. Steel also has a conductivity about half that of brass, which limits braking current, which can be a safety issue. Three year warranty but shipping at my expense and all I get is another one with the same defects. . I threw it away and bought it with brass contacts. Now there are no problems with corrosion.