7318.21.00.90 - Other

This HTS category, "Other" under 7318.21.00.90, encompasses spring washers and other lock washers of iron or steel that do not fall into the more specific helical spring lock washer category. It includes a variety of fasteners designed to prevent loosening of bolted or screwed connections by exerting a spring force between the fastener head and the substrate. Examples can include split washers (also known as crinkle washers or Danish spring washers), star washers (internal or external tooth washers), and wave washers that provide elastic take-up.

The key distinction from the sibling category 7318.21.00.30 lies in the design and mechanism of the spring action. While helical spring lock washers are characterized by their coiled, helical shape and their action of twisting to create tension, the "other" category covers washers that employ different spring principles, such as the bending of a split section or the radial deformation of serrated teeth, to achieve their locking function. The material remains consistent with the parent category, limited to iron or steel.

As this is a leaf node in the HTS structure, there are no further subcategories. Therefore, classification within 7318.21.00.90 relies on a thorough examination of the physical characteristics and the specific locking mechanism of the washer in question to ensure it is not classifiable under the more specific helical spring lock washer heading. The "other" designation serves as a residual category for all qualifying lock washers that do not fit the more narrowly defined subheadings.