Just a Word of Advise.
If you are Trying to work at a Precise Temperature, say 150F, do yourself a Favor and buy a Decent Thermometer.
Things like Crock Pots are Notorious for Being Off of what the Numbers on the Dial say to what the Actual Temperature is.
Thanks zoidman -
I totally agree and should have mentioned this. Here is what I use:
3 Pcs LCD Digital Fish Aquarium Thermometer Water Black Free Extra Batteries | eBay
I bought 3 of these for under $10.00. I cannot tell if any individual one is calibrated, but using two at a time (that read the same) gives me a feeling of compliance...