I have had these seats in my Miata for about 10 years and 20,000 miles. They are no longer produced by Sparco. They are a good compromise between ease of entry and support. Perfect for a daily driver that sees some track and autocross use. I removed them because I am now tracking my car and the harness holes are too low for me. I am 6' tall, 180 lbs and I have somewhat short legs. I usually drove the car with the seats two clicks forward from the furthest back position.
They are lightweight fiberglass bucket seats, with custom 5mm (3/16") thick 6061-T6 aluminum side mount adapter brackets that bolt onto the stock sliders.
The seats sit as low as humanly possible on the stock sliders. The bottom of the fiberglass bucket sits about ~8mm from the carpet. You can barely squeeze a sharpie marker in between the bottom of the seat and the carpet. The bottom cushions can also be removed if you need to sit really, really low. The custom mounts have three recline positions.
The fiberglass buckets have been shaved down in the outer shoulder areas, and near the transmission tunnel. The trimming included clearance for hardtop latches.
They are faded pretty bad. I considered dying the covers but never got around to trying it. However there are no rips, holes or tears anywhere on the seats. In fact there isn't really any noticeable wear on the fabric anywhere.
If you are installing in a 94-97 and want to use stock seatbelts, you will need the seatbelt receivers from a 90-93, which bolt to the transmission tunnel. The threaded mounting anchors were still welded to the tunnel on my '94 from the factory.
A decade ago these were $550 each, not including the modifications and custom brackets and sliders. Asking price is $850 shipped for the pair, including the custom brackets and modified stock sliders. Literally a 5 minute install.