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.
Bought these for my daughter. She complains that they are dull, and she must use force to inject them. Also, the internal needle is bent on about 1 in 10, so they don't pierce the pen properly. Not recommended.