Power generation utilities, oil and gas operators, marine shipping, and heavy industrial manufacturers are the primary end-users. Gas turbine generator sets are particularly significant for grid infrastructure projects, while internal combustion engines serve a wide range of mobile and stationary applications.

When an engine and transmission are imported as a functional unit, HTS classification typically follows the principal function or the component that gives the assembly its essential character. This determination can be complex and should be reviewed with a licensed customs broker, as misclassification can result in underpayment of duties or incorrect trade-remedy application.