... 3,4,6,7,10, Copper-aluminum connecting pipe & air conditioner parts(1)OD:1/4,&3/8,&1/2,&5 ... 4, good insulation properties: air conditioning is needed to connect pipe insulation, and to improve the air conditioner's energy efficiency, should ... only to ensure strength and relative connecting copper pipe is easier to install and transfer machines. Copper-aluminum connecting pipe & air conditioner parts