Pretty sure that's an old school mechanical thermostat. There's not a lot of good to be had there.
And the seller is bull****ting you about digital controllers. I own a Love TSS2-2100 two-stage controller, two Ranco ETC-11100 single-stage controllers, and an MH1210 single stage controller - all of them digital - and none of them lose their settings on a power outage.
If you could install that thing, you can build a controller around the very popular STC-1000 dual-stage digital controller, which all-up would cost about the same as the mechanical, but offers much finer control and a compressor-protecting Anti-Short-Cycle function. You could also use an MH1210 - which is single stage and suitable for a dispensing system (kegerator/keezer) which can be found for a few bucks less than the STC-1K.
Either of them would be preferable to a mechanical thermostat, imo...