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.
This is going to sound so gross, but it is so satisfying to just be able to remove all the dead skin so easily and quickly. I usually soak my feet first before using just to make it a little bit easier. This works great I even bought one to keep in my travel bag so I can have it on the go as well!