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.
I bought this for everyday use, because I wanted a diffuser which I can carry with me as I like to go on weekends away. So far I have managed to fit it to every hairdryer (5+ different models), but it can be difficult on bigger hairdryers. Overall would recommend and buy again, but removed one star as it does tend to collapse when not used carefully.