3916 - Monofilament of which any cross-sectional dimension exceeds 1 mm, rods, sticks and profile shapes, whether or not surface-worked but not otherwise worked, of plastics:

Heading 3916 encompasses various semi-finished plastic articles, specifically monofilament with a cross-sectional dimension exceeding 1 millimeter, as well as rods, sticks, and profile shapes. These items are generally surface-worked, such as by coloring or polishing, but have not undergone further processing like cutting to specific lengths or assembly into finished goods. The key criterion for inclusion here is the shape and the fact that they are not further worked beyond surface treatment.

This category is distinct from other headings within Chapter 39 which might cover raw plastic materials (e.g., Chapter 3901-3915) or finished plastic articles. Unlike raw polymers, these are pre-formed shapes. They are also differentiated from other worked plastic shapes by the specific dimensions and forms mentioned in the description, and crucially, by the absence of further manufacturing steps beyond surface working.

Within Heading 3916, the subcategories are based on the specific type of polymer used. Subheadings differentiate between articles made from polymers of ethylene (3916.10), polymers of vinyl chloride (3916.20), and all other types of plastics (3916.90). This breakdown allows for precise classification based on the material composition of the monofilament, rods, sticks, or profile shapes.