The chain itself is classified by its type (roller, articulated, welded link, etc.) within this heading. Sprockets are mechanical drive components and are generally classified in the machinery chapters rather than here. Connecting links that are integral parts of the chain assembly may follow the chain's classification, but composite shipments should be reviewed under the General Rules of Interpretation.

Roller chain has cylindrical rollers mounted on the link pins that reduce friction against the sprocket teeth, making it the standard for bicycle, motorcycle, and industrial power-transmission drives. Other articulated link chain lacks these rollers and is used in applications such as conveying or lifting where the roller mechanism is not required.