Here is the conversion chart for the XR9:
4 (2427) 907
5 (2432) 912
6 (2437) 917
7 (2442) 922
I have searched, and searched, and searched to finally find it in a forum post on UBNT.com.
Please archive this for others. It was a pita for me to find. Guess I should have not put the sticker in a box that is 300 feet in the air huh