The See All PLX18 circular acrylic indoor convex security mirror is a circular, convex, acrylic mirror, with an 18" diameter, that reflects a wide angle image at a diminished size to extend a field of view to help a person see around obstacles for safety, or monitor a wide area for efficient surveillance. Acrylic is shatter resistant, weighs less than glass, and reflects a clear, bright image. The mirror comes with a swivel mounting bracket that makes it adjustable to a wide range of angles. The 18" diameter size is suitable for areas up to 15' away from the mirror (diameter is measured from the outside of the 3/4" rim). This mirror has a tempered hardboard backing for good strength-to-weight ratio in indoor applications. Tempered hardboard is a high-density fiberboard that has been coated with linseed oil and then baked to increase its water resistance, rigidity, and tensile strength. Safety mirrors are used to help increase visibility in a variety of locations; for example, in hallway intersections and sharp turns, and in driveways and loading docks where drivers have to back up or enter traffic. Safety mirrors are sometimes called security mirrors, and they can be used to extend the view of security personnel, or to help monitor factory workers and automated processes to improve quality control and productivity. For convex mirrors, objects will appear to be further away than they are, and will be easier to see in a larger mirror. Depending on visibility conditions and the viewer's eyesight, objects will usually be recognizable within about 1 ft. of distance (including distance from eye to mirror, and from mirror to object) for each inch in mirror diameter. See All Industries manufactures safety and security mirrors. The company, founded in 1958, is headquartered in Chicago, IL. What's in the Box