Product review (3 stars): One of Four- DEAD ON ARRIVAL
Six bucks apiece including shipping ain't bad.  However, when one of four units purchased failed to light off upon installing the tested battery, the deal ain't so good.  The remaining three operating units compare within two degrees F of a calibrated standard, and within 1% RH.  Time and date are good, but I got these for the RH feature.  If all of the purchased units worked, I'd give this FIVE STARS for function and value.