Cabinet temperature control devices, installed on a DIN rail.
CD (blue adjustment screws) = with a normally open contact. Can be used for temperature alarm signalling or for controlling ventilation systems.
TMC (red adjustment screw) = with normally closed contact. It can be used either as an alarm signal or for controlling heating or anti-condensation heaters.
TEM to be electrically powered, it differs from the previous ones as it has exchange contacts, a very low intervention differential or hysteresis