They are composed of an inner and outer layer of PE-Xb, that are bonded by special glue to the intermediate layer of aluminum. ASTMF1335-1998 standard called them” metal pipes with plastic protective layer”.
Specification: coil pipe: dn16-32, length: 100m/coil
Straight pipe: dn16-dn32 4m/piece
Customized specification also available.