This is a genuine BMW window guide web cover for the left side of the vehicle. The part number is 51357205753. It is designed to cover and protect the window guide web, which helps to guide the window as it is rolled up and down. This cover is specifically designed for BMW vehicles and is made with high-quality materials to ensure durability and a perfect fit. It is an essential component for proper window function and can be used as a replacement for damaged or worn out covers.