The design starts with a solid core conductor made of 99.99% ( 4N ) Pure OFHCC copper, and a tightened grain structure ( cryo -treated ). The core is then surrounded with a surface-polished, thick layer of 99.999% ( 5N ) purity grade silver. The exact ratios are proprietary, but the silver sheath is thicker and better bonded than most designs. This hybrid conductor is then covered with a non-porous PTFE ( Teflon ) insulator, which is known for extremely low capacitance. Finally, these conductors are twisted together at a very specific rate to reject electromagnetic interference.