## Common ground
All options refer to salad washers—small, circular components used to secure bolts or screws, typically under a nut or bolt head.
## Options at a glance
**3924.10 – Made of plastic material**
- **Defining trait:** Constructed from plastic, offering lightweight, corrosion-resistant, and non-conductive properties.
- **Typical examples:** Plastic lock washers for electronics, food-grade washers in kitchen appliances.
- **Best fit when:** The product is used in environments where rust or electrical conductivity must be avoided, or where weight and cost are key factors.
**7323.9X – Made of iron or steel**
- **Defining trait:** Manufactured from ferrous metal, providing high strength, durability, and resistance to deformation under load.
- **Typical examples:** Heavy-duty washers in machinery, automotive assemblies, industrial equipment.
- **Best fit when:** The application requires high mechanical strength, long-term reliability, or resistance to high pressure and vibration.
## Key differences
| Feature | 3924.10 (Plastic) | 7323.9X (Iron/Steel) |
|--------------------|--------------------------|----------------------------|
| Material | Plastic | Iron or steel |
| Strength | Low to moderate | High |
| Corrosion resistance | High | Low (unless coated) |
| Electrical conductivity | Non-conductive | Conductive |
## How to choose
- Is the washer used in a moist, corrosive, or electrical environment? → 3924.10
- Does it need to withstand high pressure, vibration, or heavy loads? → 7323.9X
## Overlaps & pitfalls
A plastic washer may be used in industrial settings if corrosion resistance is critical, while a steel washer might be coated (e.g., zinc-plated) to prevent rust—still falling under 7323.9X. The main function determines the classification: if the primary purpose is mechanical strength, use 7323.9X; if it's insulation or lightweight use, use 3924.10. No priority rule can be assumed—choose based on the product’s **main function**