 The first stage pin connectors had two cylindrical pins, one for line (hot) and one for neutral, arranged symmetrically in a rectangular housing.The housing was milled from a solid block of fiberglass or bakelite which may have been impregnated with asbestos for fire resistance, with a screw-on cover.Later connectors (including those currently manufactured) use molded plastic or machined phenolic resin laminate housings .