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.
As they’re cheap, you get what you pay for. First ring I tried to adjust snapped in half straight away. Only one I found to be adjustable to smaller sizes. Don’t waste your money if you plan to adjust them!