NAICS 33399 includes power-driven handtools (333991) and welding and soldering equipment (333992), along with other machinery not classified elsewhere in the general-purpose machinery sector.

Machines designed for multiple functions or industries can be classified under different HTS chapters depending on their primary use — for example, a machine that both cuts and welds may be claimed under either a cutting-machine or a welding-machine heading. CBP's primary-function test and the importer's intended use both factor into the determination, making pre-entry classification review advisable for multi-function equipment.