This special scientific calculator is see-through and works on solar energy. Produced by Stokes Publishing Co from California, USA together with Texas Instruments. Made in 1993, it was aimed to being used on overhead projectors featuring a light source and projecting slides on a screen with some magnification and as called the 30X – The Educator. It is a working and like new with all the accessoires like manual, pouch, garante card and still in plastic. It is working fine and there are hardly any signs of use and age. The box is complete and in good condition as well. The box measures ca 23 cm or 9 inches wide. Do check the attached video for a vintage calculating tour!