## Common ground
All options refer to transparent coverings for clocks or watches, protecting the face while allowing visibility.
## Options at a glance
**3926.90 – Plastic material**
- **Defining trait:** Made from synthetic polymer (plastic), typically lightweight and impact-resistant.
- **Typical examples:** Acrylic, polycarbonate, or resin watch crystals.
- **Best fit when:** The cover is flexible, shatterproof, or used in sport watches and budget timepieces.
**7015.90 – Glass**
- ****Defining trait:** Made from mineral (soda-lime) or tempered glass, offering higher scratch resistance.
- **Typical examples:** Hardened glass on luxury watches, vintage timepieces, or precision instruments.
- **Best fit when:** The cover needs durability against scratches, high clarity, or a premium feel.
## Key differences
| Feature | 3926.90 (Plastic) | 7015.90 (Glass) |
|------------------|--------------------------|--------------------------|
| Material | Synthetic polymer | Mineral/tempered glass |
| Scratch resistance | Low to moderate | High |
| Impact resistance | High (shatterproof) | Moderate (can crack) |
| Common use | Sport, casual, low-cost | Luxury, precision, classic |
## How to choose
- Is the cover made of a flexible or shatterproof material? → 3926.90
- Does it feel hard and smooth like glass, with high clarity? → 7015.90
## Overlaps & pitfalls
A product may combine both (e.g., plastic with scratch-resistant coating), but the primary material determines classification. If unclear, prioritize the **main structural material**—plastic vs. glass. Do not assume "glass" includes all transparent covers; only mineral or tempered glass qualifies under 7015.90