Genuine OEM Mercedes-Benz Screw, part number A0004312271. This screw is used to fasten the expansion reservoir to the brake master cylinder, ensuring a secure and leak-free connection. It is made of metal and has dimensions of 0.06m x 0.01m x 0.01m. Genuine OEM fasteners are manufactured to exact specifications, guaranteeing the correct thread pitch and material strength for critical brake system components.