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.