## Common ground
Both options are solar tunnels for roofs, designed to channel natural light into indoor spaces.
## Options at a glance
**3925.90 – Plastic material**
- **Defining trait:** Constructed primarily from durable plastic (e.g., polycarbonate), offering lightweight and cost-effective light transmission.
- **Typical examples:** Polycarbonate roof lights, translucent dome skylights, flexible solar tubes.
- **Best fit when:** Budget-friendly installation, moderate climate, or where weight is a concern (e.g., older roofs).
**7610.90 – Aluminium**
- **Defining trait:** Made of aluminium, providing higher strength, durability, and resistance to weathering and deformation.
- **Typical examples:** Metal solar tubes, reinforced roof skylights, industrial-grade daylighting systems.
- **Best fit when:** Long-term use, harsh weather (high wind/snow), or high structural demands (e.g., commercial buildings).
## Key differences
| Feature | 3925.90 (Plastic) | 7610.90 (Aluminium) |
|------------------|--------------------------|----------------------------|
| Material strength | Lower | High |
| Weight | Light | Heavier |
| Durability | Moderate (can degrade) | High (resists corrosion) |
| Cost | Lower | Higher |
## How to choose
- Is the installation on a lightweight or aging roof? → 3925.90
- Will it face extreme weather or heavy loads? → 7610.90
- Is cost a major factor? → 3925.90
- Is long-term durability critical? → 7610.90
## Overlaps & pitfalls
A solar tunnel may use both plastic and aluminium (e.g., plastic lens with aluminium frame), so it could fit both codes. If the product’s main body is plastic, use 3925.90; if the primary structure is aluminium, use 7610.90. The defining trait should be based on the **main structural material**