When installing a standard split AC or heat pump system you sometimes need a transition piece to connect the larger refrigerant line (suction line) to the evaporator coil (indoors), and/or condensing unit (outdoor unit).

• A 3/4 inch stub will slide perfectly into a 3/4 inch suction line connection on the evaporator coil and/or condensing unit. 
• If using a 7/8 inch suction line, the 7/8 inch suction line will slide securely over the 3/4 inch stub. Then you braze the copper. 
• The 3/4 inch stub can be used to allow an evaporator coil or condensing unit that has a 3/4 inch suction line connection (larger refrigerant line) to use 7/8 inch suction line when needed. 
• There is a basic visual representaion in the documents section below