What's the deal with Boveda Hygro Calibration Kit?

[ak2000]

So I picked up a new Hygrometer from Heartfelt along with the Boveda Calibration Kit. It says 75.5% RH gauranteed accurate on the kit. Both my digital Credo and the new Hygro from Heartfelt read 70% in the pouch after 3 days. Are both of these Hygros wrong or is the kit actually 70%, which would make more sense to me. Isn't the "salt test" 70%?????????