The Genuine BMW Micro Switch Rear Window Lock (part number 61318355127) is a small electronic component used in BMW vehicles to control the locking mechanism of the rear windows. It is a genuine BMW product, meaning it is made by the original manufacturer and is of high quality. The micro switch is responsible for detecting when the window lock is engaged and sending a signal to the window motor to prevent the rear windows from being opened. This product is designed specifically for BMW vehicles and is an essential part of the window locking system.