I am very pleased with the main functionality of this item. However, it is a fiddly operation if you find that you need to remove it when you do not need the limited angle of visibility - such as when working from home. One laso has to accept that the screen brightness will have to be on maximum when this item is attached as it reduces the amaount oof light coming through.
This is so comfortable for me. After typing and scrolling through a thesis I found my wrist was very painful and wondered if I could ever use a "normal" mouse again. This device has helped me get over the discomfort of moving the mouse completely.