Amazon calculates a product's star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
Product provided is not what is pictured. Product provided is Tumbler which is typically referred to as medium and not large. Product in picture is larger than the 12oz size in description. Bottom is very thin and cracks easy because it is not identified, concave like better quality glasses.