THESE MICROCLIMATE THERMOSTATS REGULATE POWER OUTPUT AND DIM THE POWER SOURCE RATHER THAN TURNING IT ON AND OFF. THIS METHOD OF TEMPERATURE REGULATION ALLOWS YOU TO USE THESE THERMOSTATS WITH INCANDESCENT GLOBES AS THE DIMMING PROLONGS THE LIFE OF THESE GLOBES. THESE THERMOSTATS CAN BE USED WITH ALL OTHER HEAT SOURCES ALSO. THEY CONTROL UP TO 600 WATTS OF HEAT SOURCE. THESE UNITS ARE FULLY WIRED WITH A FLEXIBLE PROBE THAT CAN BE POSITIONED INSIDE THE VIVARIUM WITH THE UNIT SITTING ON THE OUTSIDE. THIS ALLOWS YOU TO DRILL A SMALL HOLE IN THE VIVARIUM TO PASS THE PROBE THROUGH. SO EASY! UNIT SIZE : 101 X 78 X 41 MM