Vivarium Electronics has designed this heat panel specifically around the needs of reptile users. For Radiant Panels to work at their best we very strongly recommend a proportional thermostat. We recommend the use of the Vivarium Electronics proportional thermostats when using panels in enclosed areas to maintain the ideal temperatures for your reptiles. Ultra easy to install (3 screws-included) and can't be climbed on by your snakes! 40 watt panel measures approximately 12.5"x12.5"x1.75" (overall dimensions).