The guy I got the wheels from shipped me these as well. He had used them for 3k and I have had them on my car for the past 3 years, they have been on and off numerous times and they have held up really well!!! They are super light and I have had one yet to cross thread.
I run them on the 949 Racing 6UL 15x9 wheels and on the front I have a 5mm spacer, they work great and I get more then enough threads with the spacers. I use an impact but don't crank them down like crazy with it. They are tough. I would recommend these for sure!!! They only weight 24 grams.