Failsafe for Fan Cooling

Does anybody know the exact part number for a thermostat that can be mounted to the heatsink to measure its heat and trigger a normally-on relay to close?

Also anybody know one that can set a dimmer based on temperature?

I just need the part number for the thermostat.

I am trying to find a thermostat that people have seen used and know it is reliable. I found a few on google but prefer opinion of somebody who is following these threads closely and can give some insight on a good tstat.

Thanks.

@REALSTYLES
@UKpeanuts @HydroDC @SupraSPL

anybody have experience with Airpax Series 6700 Thermostat ?

seems to be readily available on Newark, and available at various temperatures.