To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
I might be missing something here as other reviews seem to be positive but this made my ring cloudy. Honestly, I don't think anything is more effective than fairy liquid and an electric toothbrush. Save your money!