Bests & Worsts Reviews from Amazon

We purchased two, but it was not until both were out of their packaging that I noticed a four-degree discrepancy! Is either accurate? How does one know? If one is accurate, which? When Taylor sent this production work to China did it not occur to someone that there should be standards? These are refrigerator/freezer thermometers. A refrigerator should be maintained at 40 or below! After placing them side by side in our refrigerator there was a six degree difference! How does one know, is it 40 or 46 or 34, or ?