http://amzn.com/B0007VWEQA

Calibrated it with this video, I do this every six months or so.

http://youtu.be/d7Ap96SlGZA

For my thermometers I use these. I bought 10 and then just picked out the ones that were the gave the same temp reading when they are placed side by side.

http://bit.ly/12mUQCt