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've been plugging everything I own into this thing to see what they draw. Not sure about accuracy, but it's easy to read and hasn't caused any issues. It's big so it'll block the ports next to it, but you're probably not going to leave this in permanently.