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.
Not universal! Doesn’t stay attached, doesn’t lock in place, flops around, is always crooked, then falls off. Even if it did stay attached, which it doesn’t, there are no center teeth, perimeter only. Too much blowing, not enough diffusing. Absolute garbage. Returned.