The casio OH-7000G is more or less an instructors version of the casio FX-7000GA graphing calculator. It has a see-thru screen so you can place it on an overhead projector. It also comes in a hard shelled case as shown in the picture. When in the case there is a metallic surface behind the screen to reflect light outwards so you can read the screen without a lightsource like an overhead projector. These are very interesting little units. I have documentation for them so if you have any questions just e-mail me and I'll look it up for you. I also have four extra ones forsale, each is new in the box still shrinkwrapped.