# HTS 9902.01.31: Amorphous silicon dioxide micro-spheres of mean particle size 0.003-0.018 mm, linseed oil absorption 30-40 ml/g, surface area less than 80 m²/g, and pore volume less than 0.1 ml/g (CAS No. 7631-86-9) (provided for in subheading 2811.22.10)

> Plain-language tariff reference from the USITC Harmonized Tariff Schedule on [PlainTariff](https://plaintariff.com/).

## Duty rates

- **General (MFN) rate:** Free
- **Special / FTA rate:** No change
- **Column 2 rate:** No change
- **Corpus rank:** #4475 of 5979 among duty-free tariff lines

## Classification path

- **Section XXII:** [Special Classification Provisions](https://plaintariff.com/section/xxii-special-classification-provisions)
- **HTS code:** 9902.01.31

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*Source: U.S. International Trade Commission Harmonized Tariff Schedule. HTML canonical: https://plaintariff.com/heading/99020131-amorphous-silicon-dioxide-micro-spheres-of-mean-particle-siz*