Standard, OFC, PCOCC & Litz 5N Pure Silver Connecting Leads. OFC (Oxygen Free Copper) Lead Wires Standard Lead Wires PCOCC (5N Litz Perfect Crystal) Lead Wires 5N Pure Silver Litz Lead Wires: 30 AWG, 5N Pure Silver Litz Wiring is the Best Wire for Faster Transmission Speeds and Cleaner Sound.