Amazon calculates a product's star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers and factors that establish reviewer trustworthiness.
Backside hanging connector came out on the first day when I was holding in my hand before I nailed to the wall. If I would have hung it on the wall mirror would have broken into pieces. So beware of this seller should know this