## Common ground
All options are fastening adapters, used to connect or secure components.
## Options at a glance
**3926.90 – Made of plastic material**
- **Defining trait:** Constructed primarily from plastic, offering lightweight and corrosion-resistant properties.
- **Typical examples:** Plastic mounting brackets, snap-fit connectors, insulating fasteners.
- **Best fit when:** The adapter is lightweight, non-conductive, or used in environments where rust or weight matters (e.g., electronics, outdoor use).
**7318.19 – Made of iron or steel**
- **Defining trait:** Constructed from ferrous metal, providing high strength and durability.
- **Typical examples:** Steel bolts with adapter sleeves, heavy-duty mounting clamps, industrial fastening joints.
- **Best fit when:** The application requires high load-bearing capacity, mechanical strength, or resistance to wear (e.g., machinery, structural assemblies).
## Key differences
| Feature | 3926.90 (Plastic) | 7318.19 (Iron/Steel) |
|---------------------|--------------------------|----------------------------|
| Material | Plastic | Iron or steel |
| Weight | Light | Heavy |
| Corrosion resistance| High | Low (unless coated) |
| Strength | Moderate | High |
## How to choose
- Is the adapter made of plastic? → 3926.90
- Is it made of iron or steel? → 7318.19
## Overlaps & pitfalls
A fastening adapter could be made of metal with a plastic coating, but the primary material determines classification. If unclear, prioritize the dominant material by weight or structure. No option is inherently more correct—choose based on the core construction material