| 90 | Optical instruments and apparatus, photographic, cinematographic, measuring, checking, precision, medical or surgical; parts and accessories |
| 9027 | Instruments and apparatus for physical or chemical analysis (for example, polarimeters, refractometers, spectrometers, gas or smoke analysis apparatus); instruments and apparatus for measuring or checking viscosity, porosity, expansion, surface tension or |
| 902710 | Gas or smoke analysis apparatus |
| 9027109000 | Other gas or smoke analysis apparatus |