## Common ground
All options are covers, rings, and frames designed for manholes.
## Options at a glance
**3926.90 – Plastic material**
- **Defining trait:** Made from plastic, offering lightweight and corrosion-resistant properties.
- **Typical examples:** HDPE or PVC manhole covers, resin-based frames.
- **Best fit when:** Used in areas needing low weight, chemical resistance, or noise reduction (e.g., residential streets, utility access).
**7325.10,7325.99 – Iron or steel**
- **Defining trait:** Made from ferrous metal, providing high strength and durability under heavy loads.
- **Typical examples:** Cast iron covers, steel-reinforced frames for roads or industrial zones.
- **Best fit when:** Required for high-load environments like highways, parking lots, or heavy traffic areas.
## Key differences
| Feature | 3926.90 (Plastic) | 7325.10/99 (Iron/Steel) |
|---------------------|--------------------------|------------------------------|
| Material | Plastic (e.g., HDPE, PVC) | Cast iron or steel |
| Weight | Light | Heavy |
| Durability | Moderate (resists corrosion) | High (withstands heavy loads) |
| Noise | Low (silent when stepped on) | High (clattering sound) |
## How to choose
- Is the cover made of plastic? → 3926.90
- Is it made of iron or steel? → 7325.10,7325.99
## Overlaps & pitfalls
A manhole cover may combine materials (e.g., plastic frame with metal insert), but the primary material determines classification. If unclear, prioritize the **main structural material**—not the secondary component. No option is inherently superior; choice depends on load, environment, and installation needs