Wow! I remember making those and they were a challenge but also fun to do. That particular R9 has all of the updates done to it at that time and we were really kicking it then. One of my favorite model R9 Pistols for sure, and that one is pristine!
Good Luck with your sale good Sir. The new owner will have a premium model defensive sidearm with this addition to their collection.
Regards,
Eric R.