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 purchased two kinds. One without the visible curb and this one. You would think this 'curb' should help, but it is absolutely useless. The receiver constantly falls off while trying to type on a keyboard.