## Common ground
All are types of laboratory equipment categorized by their primary material composition.
## Options at a glance
**3926.90 – Made of plastic**
- **Defining trait:** Constructed primarily from synthetic polymer materials, often lightweight and chemically resistant.
- **Typical examples:** Beakers, pipette tips, petri dishes, storage containers.
- **Best fit when:** The equipment is non-metallic, flexible or disposable, and used with corrosive or reactive chemicals.
**6903 – Made of refractory ceramic**
- **Defining trait:** Designed to withstand extremely high temperatures without degrading.
- **Typical examples:** Crucibles, furnace linings, high-temp reaction vessels.
- **Best fit when:** The equipment is used in high-heat processes like calcination or melting.
**6909.1X – Made of ceramic**
- **Defining trait:** Non-metallic, inorganic material with moderate heat and chemical resistance; typically rigid and brittle.
- **Typical examples:** Porcelain dishes, mortar and pestle, some lab stands.
- **Best fit when:** The equipment needs durability and resistance to moderate heat or chemicals but not extreme temperatures.
**7017 – Made of glass**
- **Defining trait:** Transparent, chemically inert, and suitable for precise visual observation and reactions.
- **Typical examples:** Test tubes, flasks, burettes, glassware for distillation.
- **Best fit when:** The equipment requires transparency, precision, or resistance to most chemicals.
## Key differences
| Feature | 3926.90 (Plastic) | 6903 (Refractory Ceramic) | 6909.1X (Ceramic) | 7017 (Glass) |
|---------------------|-------------------|----------------------------|-------------------|--------------|
| Heat resistance | Low | Very high | Moderate | Moderate |
| Transparency | Usually opaque | Opaque | Opaque | Transparent |
| Chemical resistance | High (varies) | Very high | High | Very high |
| Fragility | Low (flexible) | High | High | High |
## How to choose
- Is the equipment transparent? → 7017
- Does it need to withstand very high temperatures? → 6903
- Is it made of a flexible or disposable polymer? → 3926.90
- Is it rigid, non-transparent, and used in moderate heat/chemical environments? → 6909.1X
## Overlaps & pitfalls
- Glass (7017) and ceramic (6909.1X) may both be chemically resistant but differ in transparency and thermal limits.
- Refractory ceramic (6903) is a subset of ceramic; use 6903 only for high-temp applications.
- Plastic (3926.90) can mimic glass in shape but lacks heat/chemical stability—don’t confuse with glassware.
- If unsure, prioritize the **main functional material** (e.g., glass for visibility, ceramic for heat)