I want to be sure you understand that you can’t equate a number on the AT to a number on the Arkray. I’ve done a ton of testing with my Micro and an AT2 and entered some of the data on a tab on Gracie’s SS. You’ll see that the numbers were never consistently a specific amount apart. I want to strongly discourage you from thinking that your two meters are always 40 apart. That’s going to give you a false sense of security.My AT2 reads abt 40 higher in 300's so 353 would be abt 313 for comparison.