The Virtual Boy provided an early, portable, 3D experience in an inexpensive package that included the full computing system in the device. As a table-mounted head display, the Virtual Boy has no possibility of head tracking or the freedom of motion available with most VR headsets. It uses Reflection Technology's scanning, mirror-style, monochromatic display in which a column of 224 LEDs is scanned across the eye with an oscillating mirror as the LEDs flash on and off, creating a 384x224 pixel resolution display with persistence of vision. It provides adjustments for focus and inter-eye distance. With over a million devices sold, the Virtual Boy introduced many consumers to immersive gameplay.