Open racks are products such as racks used in places such as optical experiments, etc. VR series open racks are used in combination with dedicated trays, etc. Because they have casters, they can be moved freely. They allow experiments and operations to be performed smoothly by efficiently storing measurement equipment and cables. The keyboard unit for an open rack has a structure that allows the tray to come out simply by pressing the front panel, so it is convenient because it can be stored when not needed. A prefabricated darkroom is a simple darkroom that can be used for each work space. It provides a darkroom effect and has the effect of blocking the air flow. There are also benchtop darkrooms for use on surface plates and desks. There are also dedicated LED lighting fixtures and exhaust fans, and exhaust fans can be selected based on the exhaust type and intake type.