The TTEC series are thermostat controllers used to regulate the temperature inside industrial control panels or cabinets and control cabinet accessories. The TTEC series control fans, heaters, and switch loads. TTEC-100 and TTEC-200 are identical except the TTEC-100 (Red) is Normally Closed which opens at temperature rise, and turns the Heater off, the TTEC-200 (Blue) is Normally Open which closes at temperature rise, and turns the Fan/Fan Filter on