drivers and necessary line transformers. Driver and tramsformer must be coverd with weatherproof cover. Each unit shall be equipped with 30 feet of outdoor speaker cable. The assembled unit shall have a guaran- teed frequency response of 125 to 7000 C.P.S. and must have a@ guaranteed efficiency rating of 112.5 db. acoustical output of 4 feet from axis of horn with one watt output. It shall have a mounting bracket, complete with hardware for attachment to a wood pole. INTERCOMMUNICATION SYSTEM: 17-30. An Intercommunication System shall be provided 17-31. Each of the installed units shall be RCA MI- in accordance with the following specifications and installed as shown on the drawings. 12589 or equal. It must be suitable for installation as an All-Master System of seven units. It must be equipped with an earphone receiver, in addition to a loudspeaker. It shall be housed in a Matte black cabinet approximately 10-3/8" x 7-1/8" x 5-7/8" with & satin chrome grill. It shall be suitable for operation on @ power source of 105/125 volts A.C., 50/60 cycles, 25 watts. The output impedance shall be 15 ohms. tubes used shall be 6 SL/7GT, 6V6GT, 6X5GT. shall be fungus proofed. 17-32. The Each unit Each of the installed sound-powered telephones shall be U.S. Instrument A-257-4 or equal complete with U.S. Instrument mount A-281 or equal. RADIO: 17-33. This Contractor shall install and operate tactical radio equipment (furnished by others) in marine office, marine craft, and warehouses as required to make his operations safe and speedy. 17-5