## Common ground
All options refer to hollow or various shaped metal products made from specific metallic materials.
## Options at a glance
**7318.15,7318.29 – Iron or steel**
- **Defining trait:** Made from iron or steel, commonly used for structural and industrial applications.
- **Typical examples:** Steel pipes, hollow shafts, metal tubes.
- **Best fit when:** The product is primarily made of iron or steel, especially in construction, machinery, or plumbing.
**7415.33 – Copper**
- **Defining trait:** Made from copper, valued for electrical conductivity and corrosion resistance.
- **Typical examples:** Copper tubing, electrical conduits, heat exchangers.
- **Best fit when:** The product is used in electrical systems or high-corrosion environments.
**7508.90 – Nickel**
- **Defining trait:** Made from nickel, known for high strength and resistance to extreme temperatures and corrosion.
- **Typical examples:** Aircraft parts, chemical processing equipment, turbine components.
- **Best fit when:** The product requires high durability in harsh or high-temp environments.
**7616.10 – Aluminium**
- **Defining trait:** Made from aluminium, lightweight with good corrosion resistance.
- **Typical examples:** Lightweight tubes, heat sinks, automotive parts.
- **Best fit when:** Weight reduction is key, e.g., in transport or consumer goods.
**7907.00 – Zinc**
- **Defining trait:** Made from zinc, often used for galvanization and sacrificial protection.
- **Typical examples:** Galvanized pipes, corrosion-resistant fittings.
- **Best fit when:** The product is coated or designed for anti-corrosion use.
**8101.99 – Tungsten**
- **Defining trait:** Made from tungsten, extremely dense and heat-resistant.
- **Typical examples:** High-temperature furnace parts, electrical contacts.
- **Best fit when:** The product must withstand extreme heat or high mechanical stress.
**8102.99 – Molybdenum**
- **Defining trait:** Made from molybdenum, used in high-temperature and high-stress applications.
- **Typical examples:** Aerospace components, furnace elements.
- **Best fit when:** The product operates under extreme thermal or mechanical loads.
**8104.90 – Magnesium**
- **Defining trait:** Made from magnesium, very light but reactive; often alloyed.
- **Typical examples:** Lightweight structural parts, aerospace components.
- **Best fit when:** Ultra-lightweight design is critical, despite reactivity concerns.
**8108.90 – Titanium**
- **Defining trait:** Made from titanium, strong, lightweight, and highly corrosion-resistant.
- **Typical examples:** Medical implants, aircraft parts, marine equipment.
- **Best fit when:** High strength-to-weight ratio and biocompatibility or corrosion resistance are essential.
## Key differences
| Material | Density | Corrosion Resistance | Heat Resistance | Common Use Case |
|--------------|--------|-----------------------|------------------|----------------------------|
| Iron/Steel | Medium | Low-Medium | Medium | Structural, industrial |
| Copper | High | High | Medium | Electrical, plumbing |
| Nickel | High | Very High | Very High | Aerospace, chemical plants |
| Aluminium | Low | Medium | Medium | Transport, consumer goods |
| Zinc | Medium | Medium | Low | Coating, protection |
| Tungsten | Very High | Medium | Extremely High | High-temp applications |
| Molybdenum | High | High | Extremely High | Extreme environments |
| Magnesium | Very Low | Low | Low | Lightweight structures |
| Titanium | Medium | Very High | High | Medical, aerospace |
## How to choose
1. Is the product primarily used in electrical or plumbing systems? → 7415.33
2. Does it need to resist extreme heat or corrosion? → 7508.90 / 8102.99 / 8108.90
3. Is weight a critical factor? → 7616.10 / 8104.90
4. Is it for structural or industrial use? → 7318.15,7318.29
5. Is it coated or used for anti-corrosion protection? → 7907.00
## Overlaps & pitfalls
- Some materials (e.g., titanium, nickel) may serve multiple high-performance roles; prioritize based on **main function**.
- "Hollow or shaped" applies to all—material is the key differentiator.
- No clear priority rule given; choose based on the product’s **primary material and intended use**