This Current type 4:1 (200:50 Ohms) BALUN is another product designed to give you peace of mind Dual double cores  total of four (4) 24 inch (61mm) wound with PTFE silver plated 14 AWG stranded wire will give you a lot of room to use it with your Doublet antenna fed by twin lead or just any other application needing 4:1 impedance transformation