My first Pro Kennex was the Silver Ace back in the early 80's. It was a graphite/fiberglass composite that only cost about $80. It was one of the cheapest graphite composites at the time and also one of the best. It had more flex than most graphite racquets, which made it comfortable and gave me confidence to take full swings. I was very upset when I cracked it and was told they stopped making it.
My second Pro Kennex is the Ki 5x, which I'm using right now. I'm very happy with it. My elbow feels much better since I switched from the APDGT, and my game is better too. It's quite a bit heavier than most modern frames, but you do get the benefit of more plow and stability.
Pro Kennex was one of the first manufacturers to make graphite racquets, and as another poster noted, they were the brains behind a lot of the technology you see from the big name manufacturers.