These things are terrible! They have the quality and consistency of something from a gumball machine or a carnival game prize. The latter comparison is appropriate, as I feel like I'm on a carnival ride when I wear them -- everything is bouncing around. There are no gradiations or "progressive" changes -- it's an abrupt line. To get the proper focus for reading or computer work, I need to hold my head up at a very steep angle. If you can stretch your neck all the way up and hold it there for a few hours while you work or read a book, then these may be for you. For the rest of us, these are a joke.