This Mirror Defogger is designed to be installed in new and retrofit applications that allow at least 1/16" (1.6 mm) space behind the mirror. The "hardwire" (non plug-in) connection ensures that the aesthetic integrity of your bath is not compromised. The adhesive surface of the Defogger is bonded directly to the back surface of the mirror. Installation is not difficult and conforms to standard industry practice. As with any electrical product, we recommend installation be performed by a qualified person, in accordance with local codes.