COLD-WELDED GOLD-PLATED PURE PURPLE COPPER RCA PLUGS: This plug design allows for a connection devoid of solder, which is a common source of distortion. Because the ground shells are stamped instead of machined, the metal can be chosen for low distortion instead of machinability. Purple Copper offers a cleaner, clearer sound than the nickel-plated or OFHC metals commonly found in competing manufacturers plugs.