The thickest conductor in the range of single pure silver speaker cables from Audio Note. Composed of 27 strands of 99.999% litz silver speaker wire. Also known as the AN-SPx speaker cable. Overall diameter 4.55mm.
Litz is composed of very fine strands of high purity copper wire insulated from each other with a fine polyeurthane coating, then bundled to form a larger gauge wire. The varnish on each strand must be scrapped off before a good solder joint can be achieved. You can flatten the wire, then use a single edged razor blade held 85-90 degrees to "shave" the varnish off the wire. After removing most of the varnish, use a 40 watt solder iron and a bit of solder to burn off the rest. A scum will bubble up and harden after the wire cools off. A solder pot can also be used to burn the varnish off.