The fittings which you are using will depict the wire type you will need.  Firstly the size on the wire needs to match the fittings e.g, 3.2mm fitting needs a 3.2mm wire – sometimes referred to as 1/8 wire.  Then decide between 7x7, 7x19 or 1x19.  7x7 and 7x19 are both flexible wires and suitable for use with handswaging e.g with Wire Kit 1 to 5.  1x19 is a more rigid wire suitable for use with hydraulic swaging e.g wire kits 12, 16 and 17.  Please note: We can do the hydraulic swaging for you for a small fee.