The MRCOOL DIY35-3858C-O DIY 5th Gen Line Set is a 35-foot indoor line set designed for 24,000 and 36,000 BTU DIY mini-split heat pump systems using R-454B refrigerant. Featuring 3/8-inch and 5/8-inch copper tubing with Pro Cable, it connects the indoor and outdoor units to circulate refrigerant efficiently between them. https://www.partshnc.com/mrcool-diy-5th-gen-35ft-3-8-x-5-8-line-set-r-454b-diy35-3858c-o