These are simply a fantastic little item. They provide a nice snap style carpet retainer. I used them on a set of Lloyd's mats I got from CJ. For the driver's side, you need to pry the existing Lloyd's grommets out to install these. Easy to pop off the washer from the back side with a flat blade screwdriver. For the passenger side (yeah, I know crumpled mats aren't a safety hazard there, just sick of them shifting) it's a simple matter to knock two holes in the mat with a 1/2" hole punch (avail at Tandy Leather.
Very happy with this item. Inexpensive, looks nice installed, and solves a problem.