Privacy screens on monitors

In my job I have access to sensitive information, and they're going to soon require privacy screens on our monitors. Are any of these better or worse than others? I have dual 22 inch widescreens, and I think they're only requiring that we have it on one screen. Kind of odd, but maybe they're just cheap. Do they restrict what you can see from a distance, or just certain angles? Not real wild about this idea, but just trying to figure out if there is one that is better than the rest and doesn't get in the way.