They are all about the same but for the cheap ones that have +/-2ºC specs. I would suggest if you have Royals that look for a DS or 1:1 to 6:1 the greater ones the working range is to far. My second suggestion is to look at the battery, they often use a 9v, AA, or AAA. Sometimes they use CR123a, SR44 (x4) or CR2. The odd balls are a pain in the butt to find. Sometimes they can be quite costly as well, (sr44 retail off the shelf run 3-6$ each my first meter used 4 and had a hard switch it sucks if you leave it on...)
