This set of pre flared copper pipe is 3/8" diameter on the liquid line and 5/8" diameter on the gas line and is used for connecting the indoor unit to the outdoor condenser unit on larger split type air conditioning and heat pump systems. The pipes are pre insulated and come complete with short neck flare nuts ready to be used. They are available in variety of lengths starting at 2.5 metres, going up to 10 meters distance, from the indoor unit to the outdoor condenser unit.