STEEL PRE-BULBED SHANK, MULTI GRIP RIVET-NUT (PLUS NUTS) GOLD ZINC FINISH
5/16-18 X .20-.280 GRIP.
ITEM # R-S31-280MG WWW.HansonRivet.com
Used these for converting a van to an RV. I found these worked extremely well in attaching to metal, and they can easily be installed using a typical impact driver. I had these "Plus Nuts" left over, a package of 100 unopened and brand new. Current cost is $1.42 each.