When a part is designed for use across multiple machine types, classification generally follows the machine for which it is principally used or, absent a clear principal use, defaults to the NESOI parts line (9024900080). If the load cell is sold exclusively as a replacement for a metals-testing machine, 9024900040 is the appropriate line. Importers should retain manufacturer documentation specifying compatible machine models to support the classification.

Grips and fixtures that are dedicated accessories to testing machines — with no independent function — are generally classified as parts or accessories under 9024.90. Extensometers, however, may qualify as measuring instruments in their own right under Chapter 90 depending on their design and function. A binding ruling from CBP is advisable for extensometers sold separately, as classification outcomes have varied.