"Please elaborate. I have never seen one."
It would be worth your time to find Lyman's web site and request a free catalog. DON'T buy direct from them tho, find someone like Midway for that.
Lyman sells the "Universal Case Trimmer" (avoid the "Accu-Trimmer) with 9 neck pilots. They also sell a "Case Care Kit" which is basically a small pedestal mounted hand cranked tool that a series of tools screw into. That includes a primer pocket cleaner, mil. crimp reamer, neck champher/debur tool (I don't care much for its debur function), and a cone shaped steel tool with a rimmed case-like base that fits into the trimmer's shell holder.
Put the cone tool in the shell holder and screw the pocket reamer (or their primer pocket uniformer if you want one) into an adapter for the cutter shaft. Then, holding the case backwards from normal, centered in the trimmer, turn the trimmer's crank and cut away at the pocket. It's all straight in line with the case because of the nose cone fitted into the neck, so the sides of the primer pockets aren't scored or cut slanted.
I have never understood why Lyman tools in general, and especially the excellant "Universal Case Trimmer", gets ignored by the printed gun media. Perhaps it's because Lyman doesn't send "free-bee tools" to writers? For instance, (I don't use one) but the Orange Crusher press is every bit as good as those painted greeen (like mine), etc., but the others get no press. And Lyman, like Lee, has some excellant tools that are unique to them, such as the tools mentioned above.
Lyman, IMHO, sells the very best pistol dies due to their excellant straight wall case expanders. (OK, so Redding is now marketing copies of the 40 year old Lyman expander design, so they work good too.)