Not really commercial, a bit bigger and colder than the standard consumer.
Can fit about 6 bodies in it.
Cost $60 at Goodwill - SCORE!

I have a handheld remote thermometer. When set on "7", thermometer reads -14F. When set on "9", it went to "LOW", ie, too low to this thing to measure. Assume -25f to -35f.

As other have mentioned, 0 is the recommendation. As Gryg pointed out, there are perfectly valid reasons to go lower if I want to pay for the electricity.

I'll keep it at -10f
for now.