Flexible, magnetic ruler. Has inches and centimeters. Helps me do exactly what I needed it to do--write in straight lines on a whiteboard. I do suggesting storing it against the side of the board to ensure that it is straight, however. I believe that a long period of time in a curved position may cause slight (hardly noticeable for me) warping. Though, it seems to be fine once I starting leaving it right against the base of my whiteboard. However, I did not get it to measure things absolutely precisely--there are hard magnetic rules for that kind of thing.
Rating: [5 of 5 Stars!]