First of all thanks Dave for even saying that I worked on a solid state amp... I don't really feel like I did cause I just change a "double flipper" pot to two single flipper pots. The two wires you see in the pic are shielded coax with stranded center conductors. Both these wires where the original and soldered on the "double flipper " pot. I didn't purchase any wires, I just un soldered them and then re soldered on the 2 pots a got. The green tape you see , I put on there so that I can tell which is the Volume and which was the reverb wire. I have no idea of the outside diameter but I guess I could measure it next time I open the amp up. By the way, there is NO markings on the wires in question and if you look at the last pic of my "problem solved" entry, you can clearly see that the same wire is used on other parts on the circuit. I hope all of this helps. G.