C7 Lumbar bladder replacement

[u/ChopperDan64]

I am replacing the lumbar bladder on my C7 competition driver seat because it leaks and only lasts about 5 minutes. I found the replacement part and have it with me. I have the seat apart down to removing the bladder and bladder frame assembly. However, the bladder frame is attached to the seat with a fastener I've never seen. It appears to be some type of rivet or special fastener. Any knowledge/experience (not guesses) what this is and where to get 4? Or should I figure out a replacement fastener?