questions about reptitemp 500r

[ScorpZion]

hey guys i got this mechanism to control the heatpad in my sand boa tank, but their is no number for it just cool and hot. it a dial you turn, my question is if i dont have a heat gun how then can i messure what to set the thhermostat on? any info would be greatly appreciated.

oh the model i have has a sensore on a cord feed back into thew box i have the sensor at the bottom under the sand as best as i could get it