Jackbox, Sound-Powered Telephone. Quadruple, submersible to 15 feet with protective cap or mating plug installed. Provides for connection of sound-powered telephone handsets or headsets. Blank plastic engraving strips, white with black core, are provided for the installing activity to mark circuit designations. Connection is made to Type 9TB4 terminal boards mounted in the bottom of the box by use of type L81 terminal lugs. Per NavShips drawing 9000-803-74210 Rev J. Mates with Symbol 2922 plug per 9-S-74211. The NSN for Symbol 2843 is 5935-00-355-4739.