Western Electric VT-1 and VT-2 Tubes
Note that VT-1 and VT-2 are the Signal Corps designations for these tubes.  The Navy designations are CW-933 and CW-931, respectively.  It was not until WW-II that the Army and Navy agreed to establish a coordinated nomenclature system (JAN, or Joint Army/Navy) which eliminated these multiple designations.