That is a ranco t-stat (the boaphile one) it is a repurposed industrial one and is a on off. I personally would recommend a herpstat 1 if you can afford the extra. I typically recommend a failsafe T-stat the herpstat 1 however protects against over temp (they all do) and under temp (only the herpstats do) and it is questionable. The use of a failsafe increases the safety margin it is used to protect against under temps.

The ranco however is perfect for an oil filled heater, most rack users use on to hold ambient and cool end temps.