A Proportional Thermostat regulates the temperature of the animals habitat by adjusting the heat source higher and lower, not just on and off.

We especially like the Herpstat line of thermostats:

• Herpstat Intro ( Link to product ) One probe and output
• Herpstat 2 ( Link to product ) Two probes and outputs
• Herpstat 4 ( Link to product ) Four probes and outputs

We prefer the Herpstat 4 for multi-rack use, however we also own multiple Helix DBS-1000’s, we have not yet replaced.  A Herpstat 4, will power 4 large racks.