The Xaralyn Built-in unit Cassette 600 built-in fireplace is a decorative electric fireplace with Opti-Myst technology without a heating function, manufactured for use in combination with a Xaralyn fireplace, but also suitable for your own designs. The reflection of the light from the lamps on the swirling water vapor gives the illusion of a flame. This Opti-Myst water vapor fireplace is an electric fireplace where water is evaporated by means of an ultrasonic evaporator. This water vapor is not hot and is lit with lamps that make the water vapor look like flames. Use: This water vapor fireplace uses a removable water tank that needs to be refilled regularly (6-7 hours). The water vapor is generated by an ultrasonic evaporator. A vaporizer lasts 6-12 months depending on use.