## Common ground
All options describe types of bearing sleeves used in mechanical or electromechanical systems.
## Options at a glance
**6909.12 – Ceramic technical sleeve**
- **Defining trait:** Made from ceramic material for high-temperature, wear-resistant, or low-friction applications.
- **Typical examples:** Ceramic bushings in high-speed spindles, aerospace bearings.
- **Best fit when:** The product is made of ceramic and used in demanding environments (e.g., heat, corrosion).
**8412.90 – Linear cylinder sleeve**
- **Defining trait:** Designed specifically for linear motion systems, such as hydraulic or pneumatic cylinders.
- **Typical examples:** Cylinder guide sleeves in actuators, linear motion guides.
- **Best fit when:** The sleeve is part of a linear actuator or piston system with sliding motion.
**8483.30 – Bearing housing (no bearings)**
- **Defining trait:** A housing that supports a bearing but does not contain ball or roller bearings itself.
- **Typical examples:** Mounting housings for plain bearings, shaft support brackets.
- **Best fit when:** The product is a structural housing for mounting a bearing, not the bearing itself.
**8505.90 – Electromagnet armature sleeve**
- **Defining trait:** Exclusively designed for use in electromagnets, typically guiding or supporting the armature.
- **Typical examples:** Sleeve inside an electromagnetic relay or solenoid.
- **Best fit when:** The product is part of an electromagnetic device and fits only the armature.
**8708.94 – Vehicle bearing sleeve (inner/outer)**
- **Defining trait:** Specifically designed for use in passenger vehicle components, such as wheel hubs or suspension systems.
- **Typical examples:** Inner sleeves in wheel bearings, outer sleeves in CV joints.
- **Best fit when:** The product is intended for automotive applications and labeled as inner/outer sleeve.
## Key differences
| Option | Material | Motion Type | Primary Use | Integration |
|-------|----------|-------------|--------------|-------------|
| 6909.12 | Ceramic | Rotational/linear | High-performance tech | Standalone |
| 8412.90 | Metal/plastic | Linear | Cylinder systems | Actuator part |
| 8483.30 | Metal | Rotational | Bearing support | Housing only |
| 8505.90 | Metal | Linear/rotational | Electromagnet | Armature guide |
| 8708.94 | Metal | Rotational | Automotive | Vehicle component |
## How to choose
- Is it made of ceramic? → 6909.12
- Is it for a linear actuator or cylinder? → 8412.90
- Does it hold a bearing but not contain one? → 8483.30
- Is it used inside an electromagnet (e.g., solenoid)? → 8505.90
- Is it for a passenger vehicle (e.g., wheel hub, CV joint)? → 8708.94
## Overlaps & pitfalls
- A ceramic sleeve in a linear actuator could fit both 6909.12 and 8412.90 — prioritize based on **primary function**: motion type (linear vs. technical use).
- An automotive sleeve might also be used in a general mechanical system — if labeled “inner/outer” for vehicles, use 8708.94.
- No option clearly prioritizes material over function; user must decide based on the **main purpose** of the product