I used RIVNUT ® RIVKLE® M8 2334 108 0230 Made by Böllhoff Inc. I bought them from the Böllhoff Canadian distributor But, as mentioned by Zyzzyx you can get them from Cardinal’s Online Store: http://www.rivnut.com/metric-rivkle-nationwide-service.htmlI want to fasten my metal shelving to my Promaster walls. There are a couple of threaded females on the walls, but these holes must serve some type of purpose for fasteners, but I'm not sure what kind. Any ideas?