This is an 11 15/16 inch x 17 15/16 inch x .04 inch see-through acrylic mirror. It can be used to make a smart mirror, an infinity mirror, used for surveillance, for theatrical applications, or whatever else you can think of. This kind of mirror is also known as a two-way mirror or sometimes as a one-way mirror. It is made of acrylic which is naturally shatter resistant, making a safer alternative to glass. Note: Make sure you peel off the protective plastic covering from both sides before use.FAQ:1. What is a two-way mirror?A two-way mirror is coated with a thin, almost-transparent layer of metal. The result is a mirrored surface that reflects some light and is penetrated by the rest. Light always passes equally in both directions. However, when one side is brightly lit and the other is dark, the darker side becomes difficult to see from the brightly lit side because it is masked by the brighter reflection of the lit side.2. How do you cut it?The acrylic can be cut, but be careful not to damage it. I would recommend leaving the protective covering on the mirror until you finish cutting and even then you may still damage the mirror in the process. You can use a plexiglass cutting tool, a razor blade, a dremmel, or a laser cutter. For a plexiglass cutting tool or a razor blade, use a straight edge and do 6-10 passes cutting all the way to the edge of the acrylic.Finally, please pay attention to care instructions on the information label attached to the mirror.