Buy with Confidence: With Monoprice's Lifetime Warranty on all Cables, you can rest assured we stand behind our products and our customers. The Plenum (CMP) rating indicates that the cable complies with fire safety and insurance requirements, making it safe for use inside the walls of residential and enterprise class buildings. This speaker Wire features conductors made of high purity oxygen-free bare copper. Monoprice plenum speaker wire uses a high quality material that is soft-er and more flexible than on traditional plenum rated jackets.