Magnetrons — self-oscillating crossed-field microwave tubes used in radar and industrial heating — go under 854071. Other microwave tubes (traveling-wave tubes, klystrons, and similar devices) that do not meet the magnetron definition fall under 854079. The distinction is the tube's internal operating mechanism, not its power level or application.

CRT picture tube subheadings (854011 and 854012) see minimal commercial volume given the near-complete transition to flat-panel displays, but the lines remain active for legacy industrial monitors, certain medical imaging equipment, and replacement parts. Importers should confirm the correct subheading because misclassifying a flat-panel display module here would be an error — flat panels classify elsewhere in Chapter 85.