I just received this reel seat for use on a lightweight spinning rod once the CRB blank becomes available. It is basically just a round graphite tube with no taper and no internal steps or ridges that would need to be reamed out for a proper fit. It is 6" long, and weighs one ounce. The I. D. is 16 mm, and the O.D. is 17.5 mm. The reel-foot opening on the smooth end is fairly small, so some reels will not fit. The hood and locking nut fit well on the barrel, with only minimal movement.
I put an old Daiwa 13 reel on the seat, then tried in both downlocking and uplocking positions. There were several problems in the downlocking position, and none in the uplocking position, so it appears that this seat was designed to be used as an uplocker. With three fingers in from of the reel and two behind it, the thumb and index finger of my average-size hand rested comfortably on the smooth part of the barrel. My pinky finger sat naturally in the groove of the metal hood, The heel of my hand rested comfortably on the locking nut, which is smoother than the nuts found on most other seats. It appears that loosening of the nut during use will not be a problem. A rear grip of any size should fit well against the threaded end of the seat without interfering with fishing or seat operation (unless you have really big hands, in which case you might want a larger size of this seat or maybe another seat altogether).
I had concerns about the large metal hood getting hot in the sunshine, but a Mudhole guy said that this should not be a problem with either hood color due to their ability to rapidly lose heat. As an uplocker, the hood would be covered while fishing.
Four stars until the rod is built and I can get in some actual fishing time, but I suspect that it will end up with five stars eventually. Definitely worth a look if you are in the market for something a bit different than standard or palm-swell seats.