391710 Artificial Guts of Hardened Protein or of Cellulosic Materials
391721 Tubes, Pipes, Hoses of Polymers of Ethylene (Rigid)
391722 Tubes, Pipes, Hoses of Polymers of Propylene (Rigid)
391723 Tubes, Pipes, Hoses of Polymers of Vinyl Chloride (Rigid)
391729 Tubes, Pipes, Hoses of Polymers of Other Plastics (Rigid)
391731 Flexible Tubes, Pipes, Hoses of Plastics
391732 Tubes, Pipes, Hoses of Plastics (Without Fittings)
391733 Tubes, Pipes, Hoses of Plastics (With Fittings)
391739 Other Tubes, Pipes, Hoses of Plastics
391740 Fittings (Ex; Joints, Elbows, Flanges)