The Rive Ray Box is a simple, safe and sturdy source of projected light for many classic optics experiments-best of all, you don't need a completely dark room to conduct optic experiments. The Rive Ray Box produces parallel, divergent or convergent rays across a plane horizontal surface and the rays are intense enough to be traced in natural light. The Rive Ray Box, with its optional accessories, overcomes all the problems inherent in a meter-stick optics system. The Rive Ray Box is durably built, with a rigid extruded vinyl base and an adjustable metal light box with mounted transformer. An adjustable screen produces either a single wide beam or a choice of one, three, or five pencil-thin rays. It operates on 115-volt, 60-cycle power, complete with a three-wire cord. Lenses, mirrors and other Rive Ray Box accessories sold separately (Catalog No. AP5659 and AP5660).