Because of many delays in the release of the Nintendo 64, in 1995 Nintendo released the Virtual Boy, a supposedly portable system capable of displaying true 3D graphics, albeit in monochromatic red and black. Despite being marketed as a portable system, it is not actually portable in practice due to the lack of head strap. Also, because of the nature of its display, the system reportedly caused headaches and eye strain. It was discontinued within a year, with fewer than 25 games being released for it. Although it sold over 750,000 units, Nintendo felt that it was a failure compared to consoles such as the Super Nintendo, which sold over 20 million.