About 2 years ago I bought NOS TTW 2.5 lb. ring weight. I wouldn’t be without it and use it (with a center weight) on all records, though when they are demonstrated it is often with badly warped ones and it does make some formerly unplayable disks sound very good. As an aside I wonder whether a PERFECTLY flat record actually exists.
Everything is improved with it. I use it on an original VPI acrylic-lead platter. It secures the disk to the platter far better and far more easily than the VPI screw clamp. It also adds flywheel. It makes light weight disks sound like heavier ones. I have paid more for smaller improvements.
They’re expensive but a lot of lesser improvements are as well. TTW is out of business but as stated above Wayne Audio (no connection) is manufacturing a similar device, "Turntable Outer Ring", formerly available on Audiogon and still available on ebay.