This is a replacement burner cap for your gas range or cooktop. The burner cap is found on the burner head, and prevents debris from getting into the head when it is not in use. The cap is black in color and is sold individually. It is a little more than 4 inches in diameter. To replace the burner cap, simply remove the damaged cap, and replace it with the new one. No tools are required for this repair. This is an OEM part from the manufacturer.