I believe they're the Summit brand sport seats. I say "I believe" because I bought them second hand. But they're identical to the Summit seats, so at the very least they're probably from the same manufacturer.
I love 'em. They do make getting in and out of the car a little more difficult because of the height of the side bolsters, but it's not that big a deal. Once in the car they're great. They're firm, but still plenty comfortable. And unlike the stock buckets they actually keep you from sliding all over the place.
Only complaint about them is some of the plastic covers, the plastic on the hinge covers and the pass throughs for the harness are pretty easy to break, most of mine are. But again, I bought mine used. Still, that's just cosmetic stuff. And for the price they're pretty much impossible to beat.