IT MOUNTS ON THE WINDSHIELD with standard Wedge mount. UNIT HAVE BEEN TEST BEFORE LISTING TO INSURE IT WORK PROPERLY AND IT IS IN PERFECT WORKING ORDER. The auto dimming will darken the mirror automatically when the cars behind you or on the side is too bright or with high bean as well as cars from opposite direction with to bright headlight or high bean.It will then clears back to normal when the brightness reduce from cars in front or behind automatically. Dealership will cost over a hundred dollars just for the mirror + time of installation. It is easy to remove and mount the new one on yourself without the technician. Good Luck and thanks for looking.... The item "2017 2019 SUBARU LEGACY OUTBACK AUTO DIM REAR VIEW MIRROR COMPASS HOMELINK" is in sale since Tuesday, September 3, 2019. This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts\Interior\Mirrors". The seller is "auctiondealonline" and is located in Sunnyvale, California. This item can be shipped worldwide.