It is made of 1/8th inch mirrored acrylic, which is stronger, lighter and more shatter-resistant than normal glass, but just as reflective.
It measures approx. 15" x 15" (custom sizes may be available). The mirror comes with 3M Command Strips, which are appropriate for affixing it to most wall covers without risk of damage.
See more of my products here: http://www.etsy.com/shop/PlainlyStated