Abbreviation for Oxygen Free Copper. As we know, copper is an element widely used as an electrical conductor in electronic equipment and wiring. Oxygen is one form of impurity in copper and can degrade the performance under some circumstances. The more pure the copper the better it conducts electricity and the more predictable its other behaviors are, which makes it a good choice for very low tolerance applications. Many ‘audiophile’ cables use OFC, though it’s debatable whether there is any noticeable improvement in sound quality.