a reusable lens / reflector unit is formed to accept a molded plastic replaceable lamp plug assembly formed to provide a hermetic seal for the lens / reflector unit . internal sealing of electrodes within the lamp plug assembly provides electrical interconnection and mechanical support for the lamp bulb in a predetermined position . a flange extends from the lamp plug body and is clamped against the socket by a rotatable collar that threads onto the socket to surround the flange and the socket .