Work great
I have ordered these twice as I tend to give them away to friends.  I wear expensive hearing aids and wearing a mask over my ears gets tangled with my hearing aids with the risk of some serious problems.  These extenders work great for getting my mask out of the way and I am very happy with the result.  Some reviews mention that they do not work well with masks with thicker cords.  This is true to a point.  I use them with KN95 masks and just have to be a little more determined to hook them around the round posts.  No issues with regular surgical masks.
Rating: 5 stars