The S-Pen with product code 'EJ-PG998BBEGEU' is compatible with the Galaxy S21 Ultra.

### Compatibility
- Samsung's S-Pen, including the one with the mentioned part number, works with the Galaxy S21 Ultra. You can use any existing S-Pen from Galaxy Note or Galaxy Tab with this device, although some Bluetooth functionality may not be available.

### Differences between models
- Specific model for S21 Ultra (EJ-PG998BBEGEU):
- This model is designed specifically for the Galaxy S21 Ultra and does not include Bluetooth features such as air gestures. It is available separately and can be purchased together with a specific case for the Galaxy S21 Ultra.

- Other model in stock (approx. 32 Fr):
- This may be an older S-Pen or a generic model compatible with the Galaxy S21 Ultra. These models may not have the same features as the specific model for the S21 Ultra, such as lack of Bluetooth functionality or different ergonomics.

### Additional functionalities
- If you want additional features such as aerial gestures and Bluetooth connectivity, you may want to wait for the release of the S Pen Pro, which includes these features.

i have a Galaxy Note 9, can i use this s-pen with a Galaxy S21 ultra ?