## Common ground
All options refer to hydraulic clutch cylinders used in motor vehicle transmission systems.
## Options at a glance
**8412.21 – Slave cylinders**
- **Defining trait:** Installed remotely from the master cylinder, actuated by fluid pressure to engage/disengage the clutch.
- **Typical examples:** Clutch slave cylinder on a car’s transmission housing.
- **Best fit when:** The component is the secondary (slave) unit in a hydraulic clutch system.
**8413.50 – Master cylinders**
- **Defining trait:** The primary cylinder where the driver’s foot pressure is converted into hydraulic pressure.
- **Typical examples:** Clutch master cylinder mounted on the firewall near the pedal.
- **Best fit when:** The component is the input side of the hydraulic system, directly operated by the driver.
**8708.93 – Clutches for cars**
- **Defining trait:** Classified as part of a complete clutch assembly for passenger vehicles (e.g., cars).
- **Typical examples:** Integrated clutch cylinder within a car’s clutch unit.
- **Best fit when:** The cylinder is permanently attached or functionally inseparable from the clutch mechanism in a car.
**8714.10 – Clutches for motorcycles**
- **Defining trait:** Specifically intended for motorcycle clutch systems, often compact and integrated.
- **Typical examples:** Clutch cylinder used in a motorcycle’s hydraulic clutch setup.
- **Best fit when:** The product is designed for use in motorcycles, not cars or trucks.
## Key differences
| Feature | 8412.21 (Slave) | 8413.50 (Master) | 8708.93 (Car clutches) | 8714.10 (Motorcycle) |
|---------------------|-----------------|------------------|------------------------|-----------------------|
| Location in system | Remote | Driver side | Integrated with clutch | Motorcycle-specific |
| Primary function | Actuation | Pressure generation | Part of complete clutch | Motorcycle use only |
| Vehicle type | Any | Any | Cars | Motorcycles |
## How to choose
- Is it the component directly pushed by the driver’s foot? → 8413.50
- Is it the remote actuator at the transmission? → 8412.21
- Is it part of a clutch assembly designed for cars (not standalone)? → 8708.93
- Is it used in motorcycles only? → 8714.10
## Overlaps & pitfalls
- A slave or master cylinder may be part of a larger clutch assembly, potentially fitting both 8412.21/8413.50 and 8708.93/8714.10.
- US Ruling H195876 clarifies that standalone cylinders (slave/master) are not classified as part of the vehicle, so use 8412.21 or 8413.50 unless integrated into a clutch unit.
- If in doubt, prioritize based on **function and integration**: standalone hydraulic component → 84xx; part of a clutch system → 87xx