do a search and you'll find more in depth info. Flexwat or sometimes referred to as heat tape is commonly used and very easy to setup especially for racks and custom enclosures. Its basically an electrical circuit in which the flexwatt is given current (electricity) and the resulting energy produced is discharged in the form heat. The heat output can be controlled by using a thermostat or other devices that regulate how much electricity it receives or simply by turning it on or off. Thermostats use a sensor which reads temperatures to determine when to make changes.
www.ASFRats.info African soft-furred rats information and exchange.