Note 8 to Chapter 39 states, “For the purposes of heading 3917, the expression ‘tubes, pipes and hoses’ means hollow products, whether semimanufactures or finished products, of a kind generally used for conveying, conducting or distributing gases or liquids (for example, ribbed garden hose, perforated tubes). The expression also includes sausage casings and other lay-flat tubing.” Thus, aside from sausage casings and other lay-flat tubing, heading 3917 is limited to tubes, pipes and hoses that are of a kind generally used for conveying, conducting, or distributing gases or liquids. Since the heat shrink tubes are used for electrical insulation and protection, they are precluded from classification in heading 3917 unless they are non-flat.