Johnson Controls A19AAT-1C
This will allow you to make any freezer into a kegerator or fermentation chamber.
The A19AAT type thermostats are single-stage cooling
controls with Single-Pole, Single-Throw (SPST)
switches that open on temperature drop.
The A19AAT type thermostats are designed to
override on-board refrigerator thermostats and provide
accurate temperature control outside of the range of
the on-board thermostats.
The A19AAT-2 model thermostat has an adjustable 20
to 80°F (-7 to 27°C) set point range, a fixed differential,
and is enclosed in a rugged steel NEMA 1 enclosure.