Laser diodes are semiconductor devices and classify under the electrical machinery chapter rather than here. Heading 9013 covers lasers other than laser diodes — such as Nd:YAG, CO₂, excimer, and fiber lasers. If the article is a module combining a laser diode with optical components, classification depends on the essential character of the assembly.

Telescopic sights designed for fitting to arms and similar aiming instruments fall under subheading 901310. However, if the sight incorporates a laser rangefinder or illuminator as its principal function, classification may shift; the heading notes and any applicable Section XVI notes should be reviewed, and a binding ruling is advisable for combination devices.