Of current interest: Adapter plug provides mobility for field switchboards

A new light compact telephone switching unit developed by the Signal Corps, Army Service Forces, is supplanting for emergency field service the bulky switchboards hitherto used. This unit, the Adapter Plug U-4/GT, can be used for terminating a local battery telephone line, and several plugs, used with a field telephone for the operator´s set, will provide a workable switchboard substitute which may be set up rapidly.