Buy with Confidence: With Monoprice's Lifetime Warranty on all Cables, you can rest assured we stand behind our products and our customers. Monoprice Plenum Speaker Wire uses an external cable jacket, which has been specially treated to resist the spread of fire. It has been CMP rated by Underwriters Laboratories (UL) as safe for use in the plenum ducts and airspaces of commercial class buildings, making it the ideal speaker Wire choice for any situation. Featuring 100 Percent pure, bare, oxygen-free copper conductors, these speaker wires faithfully and accurately reproduce music with total sonic clarity.