Pure Bare Copper: Pure Bare Copper is a superior conductor to the copper clad aluminum (CCA) conductors used in many other inexpensive speaker wires. CCA is only about 68% as conductive as pure bare copper; its additional resistance adds to the impedance of a speaker, negatively affecting its sound. CL3 In-Wall Rated: The CL3 rating indicates the cables compliance with fire safety and insurance requirements. It is safe for use inside the walls of residential class buildings. A CL3 rating can carry a surge of up to 300 watts, which is double what a CL2 rating can carry (150 watts). Using Pure Bare Copper speaker wire ensures that the total load put on the amplifier remains as close as possible to the impedance curve of your speakers. Each conductor in the speaker wire is jacketed with color-coded PVC for easy polarity identification.