Customs does not classify a part by how it looks but by what it is and what it does. So when a shipment leaves Mexico, checkout has a step before the shipping method.
What you enter
- Industry: automotive, aerospace, medical, industrial… Chosen once for the whole order.
- Prototype or production: also once. Prototypes may be treated differently by some customs authorities.
- What each part does: a short description of its function ("motor mount bracket", "guide bushing"), not of the material.
- Tariff code: 10-digit HTS code for the United States and 6-digit Harmonized System code for other countries.
You do not need to know the code
"Suggest a code" searches the official tariff for the function you wrote and proposes three codes, each with its official description. If you already have yours, typing it shows its description so you can confirm it is right.
What you see at the end
The estimate of duties and taxes for your country, including the carrier's advancement fee and the total to pay on delivery. If your parts qualify for a trade agreement, the estimate already applies it.
Afterwards
What you enter goes to your order and to the customs papers. If on review we see a code that does not fit, we correct it and the record keeps what you declared and what PREMSA corrected.