The Zoo Med Creatures Creaturetherm Heater is designed for use exclusively on glass tanks. Easily attached to the side of the tank, the installation will take mere minutes. The 4 watt output of the unit may seem small, but it does an incredibly effective job at regulating and maintaining the optimal temperature for creatures such as spiders, beetles and other small invertebrates. The Zoo Med Creatures Creaturetherm Heater is easily attached on the outside of the tank and stays out of the way of the action. Because of this, the unit is not subjected to wear and tear or moisture issues from increased humidity.