3917.10 - Artificial guts (sausage casings) of hardened protein or of cellulosic plastics materials:

This category, 3917.10, specifically covers artificial guts, commonly known as sausage casings, manufactured from either hardened protein or cellulosic plastics. These materials are engineered to mimic the properties of natural casings for use in food processing. The "hardened protein" aspect generally refers to materials derived from animal collagen or similar proteins that have undergone a process to achieve a rigid, tubular form suitable for filling.

Distinguishing this category from its siblings, 3917.10 is unique in its focus on artificial casings rather than general-purpose tubes, pipes, and hoses. While sibling categories such as "Tubes, pipes and hoses, rigid" or "Other tubes, pipes and hoses" encompass a broad range of extruded plastic conduits for fluid transport, 3917.10 is narrowly defined by its specific application as a food-grade casing. Similarly, "Fittings" (3917.40.00) are components used to connect tubes and pipes, not the casings themselves.

The subcategories within 3917.10 further refine classification based on the primary plastic material. "3917.10.10.00: Of cellulosic plastics materials" denotes casings derived from cellulose derivatives, such as regenerated cellulose (cellophane) or other chemically modified cellulose. The remaining subcategory, "Other," would encompass artificial guts made from protein-based materials, as well as any cellulosic plastic-based casings not specifically enumerated in the preceding subcategory. This division allows for precise accounting based on the distinct manufacturing origins of these specialized products.