You are correct, that is a Fox pipe. I had the first tuned pipe in my club and it was one of those. Duke Fox made his own for a while back in the late 70's-early 80's. They were machined from an aluminum block. The "ray-gun" looking rings were to keep the sides from vibrating and humming with the resonance pulses. Before he put those on the pipe, it was very loud. They did work well on a Fox .45.