Copper-aluminum connecting pipe & air conditioner parts 1)Copper tube:OD:1/4,&3/8,&1 ... :3,4,6,7,10, Copper-aluminum connecting pipe & air conditioner parts(1)OD:1/4,&3/8,&1/2,&5/8 ... needed to connect pipe insulation, and to improve the air conditioner's energy efficiency, should further improve the connection pipe ... install and transfer machines. Copper-aluminum connecting pipe & air conditioner parts