The MRCOOL NV25-3834-O Central Ducted 25 ft 3/8 x 3/4 R-454B No-Vac Pre-Charged Line Set is a refrigerant connection assembly designed for MRCOOL central ducted HVAC systems. It uses a 3/8-inch liquid line and 3/4-inch suction line to circulate R-454B refrigerant between the outdoor condenser and indoor air handler, supporting efficient heat transfer. https://www.partshnc.com/mrcool-no-vac-pre-charged-line-set-nv25-3834-o