This part will only replace the folding motor mechanism inside which usually causing problem if defective. Half way folding or not folding at all when you try to fold the side mirror using the knob. Better to purchase the folding motor itself than replace the whole side mirror assembly which usually the dealership offers. You will save a lot of money. To replace the motor, you need to detach the side mirror from the door, remove the back cover, unscrew and replace the folding motor inside. If in doubt in your car model, contact us in FB or IG and send us the front view of your car. Updates: Our folding motor is brand-new and performs better than the original due to upgraded used materials. Mazda 3 17-19 BN Sample Mazda 3 14-16 BM