That's interesting that it comes with a 30 degree calibration. Seems like 0 and 90 degrees are the 2 i have seen. Why 30 degrees?It is a really nice measurement microphone.
I have it myself, and I have checked the 0 degree calibration (it also comes with a 30 degree calibration).
For the price it is difficult to find something better, I have used it extensively with both REW and Audiolense.