Copper Tubing is the material used for the Line Set that transports refrigerant between the indoor and outdoor units. We use high-grade, ACR-rated (Air Conditioning and Refrigeration) copper because of its excellent thermal conductivity and resistance to corrosion. In our Armbridge Pre-Flared Installation Kits, the tubing is already insulated and flared for a "Braze-Free Connection." It is essential that the tubing is kept clean and dry during installation to prevent compressor damage. In a Multi-Zone installation, several hundred feet of copper tubing may be required to reach every room. Copper is the industry standard for Single-Zone systems due to its reliability under high pressure. Proper bending of the tubing prevents "kinks" that can restrict refrigerant flow and lower efficiency. It is the literal "artery" of your home's climate control system.