The MRCOOL NV15-3834-O Central Ducted 15 Ft 3/8 x 3/4 R-454B No-Vac Pre-Charged Line Set is a factory-prepared refrigerant piping assembly designed for compatible central ducted HVAC systems. It works by providing a sealed pathway for refrigerant to circulate between the outdoor condenser and indoor air handler, supporting efficient heating and cooling. Pre-charged with R-454B refrige... https://www.partshnc.com/mrcool-no-vac-pre-charged-line-set-3-8-x-3-4-model-nv15-3834-o