The Genuine BMW Door Mirror Trim Ring - 51321977684 is a replacement trim ring for the door mirror of a BMW vehicle. It is a genuine OEM part made by BMW and is designed to fit and function exactly like the original trim ring. This trim ring is made of high-quality materials and has a sleek and stylish design. It is used to cover and protect the mounting screws of the door mirror, giving it a clean and polished appearance. This trim ring is compatible with various BMW models and is an essential component for maintaining the overall look and functionality of the door mirror.