The 509.04 AAB has several different properties vs the 509.02. The main difference is in take-off performance, which is a KPIV to CSS. As you know, we were failing cold CSS testing early on. We have seen more success recently with some code fixes, but we wanted to deliver previous capability that reflects improved margin in the system. The .04 has an improved pitch during take-off which moves the lap pads on the leading edge out of interference more quickly. Our modeling and testing suggest that faster pitch has improved the CSS margin of the AAB so it is a better solution for our drive. So that's the reason for the change to the .04 overall. The change on CRT2 just reflects the drive team wanting to carry forward with a CRT2 test bed on the go forward design path. My understanding is that CRT2 is still a backup path, but we want the backup to be on the NPD POR AAB, which is essentially what the .04 is right now even though we haven't made a general migration.