Do NOT buy anything from BestNest.com and do NOT buy the "AcuRite Wireless Digital Refrigerator / Freezer Thermometer". The thermometer does not work in older fridges (such as the majority of the fridges we use for beer fridges, right?) or ones with any metal shelves. It can't get a signal through to the main unit outside of the fridge. It's all a piece of worthless crap.
Now, here's the really fun part. The online shop (BestNest.com) I bought mine from is being a real ass about it, and refusing to accept a return on it AT ALL because it has already been opened and used. They weren't even polite about it. I STRONGLY advise AGAINST buying anything from BestNest.com, EVER. I certainly will never do so again.