... the most advance technology in copper process, Rolling-Casting. Inner-grooved Copper Tube is of high cleanliness ... pin holeStandardAISI, ASTM, BS, DIN, JIS, ENMaterialRed copper, brass copper, and so onOutside Diameter4mm~60mmWall Thickness0.25mm~5. ... have passed the ISO inspections.ApplicationAir conditioners, combination type air conditioning units, refrigerators, freezers, solar water heaters, ...