Another ambiguous situation arises with the connectors used for USB, FireWire (IEEE-1394), HDMI, and Thunderbolt serial data bus connections. Close examination of these connectors reveals that the contact "pins" are not actually pins, but instead are conductive surfaces that slide past each other when they mate. Therefore, the traditional pin and socket nomenclature is not applicable. Instead, most computer hardware people fall back to referring to the wrap-around metal shield on the plug connector "as if" it were a connector "pin". By this convention, the connectors on serial bus cables are "male plugs", and the corresponding connectors on equipment are "female jacks". A unique connector configuration where the contacts are hermaphroditic is the ELCO Varicon where the contacts are bifurcated and nest with one another axial at a 90 degree rotation in cross-shaped wells. In this case the plugs had the contacts oriented transversely and the sockets longitudinally.