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.
It works as advertised, however the button to change the attachments are quite fiddly and difficult to press. Takes a few tries. It also overheats, so you have to let it take breaks. However it's cheap