The windstop comes with four straps to attach it. The two long straps go around the headrests and the short straps plug into two buttons holding the boot cover. Unfortunately, when Mazda removed the tie down straps from the boot cover, they apparently also moved the buttons a bit. So my button straps would simply not reach. Fortunately, it only takes 5 minutes to drill two new holes for these straps in the soft Plexiglas. If you have a 1996 car but no drill, make sure to give Keith the correct distance between the outmost two of the five boot buttons on the "deck".
The main straps, holding the stop to the headrests, fit well. But I felt the straps were cut pretty short, and worried that one might conceivably come loose at highway speeds if it worked a bit or was not fastened well. There are significant aerodynamic forces on the stop at such speeds. So I bought a fabric glue, "unique stitch", and glued the straps so that they could not slip. Better safe than sorry.
With a side-impact protection bar behind the seats, the stop limits the maximum backward travel of the seat backs slightly. If you like your seats that far back, you may want to drill two holes to accommodate the bar.
The usefulness of the windstop is most clearly demonstrated by the fact that I keep the stop in my "trunk". Any Miata owner knows the price of real estate in the "trunk". I do believe the car looks better without any windstop behind the seats, (and with the side windows down, for that matter.) But when it becomes colder, but still too nice to put up the top, I put on the windstop. I also put the windows up: you need to create a box for the windstop to be effective. It keeps the cold drafts out, the heat inside the car, and as an added benefit it keeps the radio clearly audible. The cold draft remains restricted to the top of your hair. I have not yet made many very long trips with my Miata, but I believe I may end up using the windstop a lot during such trips in order to reduce fatigue.