The Weber "Gourmet Barbecue System" grill, with product code 8834, is designed to be compatible with some Weber grill models, but is not necessarily compatible with all models.

To determine if this grill is compatible with your Weber Spirit 300, you should check the specifications of your grill and compare the dimensions and features of the grill. Here are some key points to consider:

- Dimensions: Make sure the dimensions of the grill (e.g. 57 cm) match those of your Weber Spirit 300.
- Grill type: The Gourmet Barbecue System grill is often designed for Weber grills that use the same cooking system.
- Specific Compatibility: You should check your grill manual or the Weber website to see if the 8834 grill is explicitly listed as compatible with the Spirit 300 model.

If you are unsure, it is recommended that you contact Weber customer service for specific compatibility information.