Air Conditioner Copper-Aluminum Line Set Our Air Conditioner Copper-Aluminum Line Set is a high-quality connecting tube assembly designed for HVAC systems. It consists of a pair of refrigerant lines (liquid line & suction line) and comes pre-insulated, making it ideal for connecting indoor and outdoor units of split air conditioners, mini-splits, heat pumps, and centralized ducted A/C systems. Applications: Suitable for ductless mini-split systems, split air conditioners, heat pumps, and centralized ducted HVAC systems. Whether for residential installations or commercial HVAC projects, it provides a reliable connection between indoor and outdoor units.