The Napoleon Trim Kit for Element NEFB36H-BS Built-In Electric Fireplace may be installed on 3 sides or 4 sides of the firebox. The Napoleon Trim Kit for Element adds approximately 5″ to sides and top, and 5″ to the bottom if installed. The Napoleon Trim Kit for Element is optional and is recommended for finishing around the NEFB36H-BS built-in electric fireplace when fitting it into an existing wood-burning fireplace or other opening. The Napoleon Trim Kit for Element creates a professional finish for openings that may not be resized to fit the NEFB36H-BS built-in electric fireplace insert.