Never seemed fair to nail the "lazy" tag so permanently on the "Susans" but that probably has no "bearing" on the issue. Also called turntable bearings, they are the square or circular flat ball bearing devices YOU bolt between two flat objects to achieve rotation. Like that spinning center section of a Chinese restaurant table. We had these in surplus once and they were quite popular. To our chagrin, we discovered they could be bought commercially for the same price. So we did. The 4" version is rated for a 300lb. load and the 12" (round) for 1000lbs.

That's what these nylon bushings were made for, but they're suitable for anything that could use a little bushing. Our middle-sized measures 15/16" dia x 15/32" thick with a 3/8" bore and a slight taper.

You pick: the sleeved bearing, sometimes listed as a "special agricultural bearing," is a single race radial bearing, 1-9/16" OD x 5/8" ID x 3/4" with a black plastic sleeve surrounding it, measuring 1-13/16" x 1" with a 1/16" wall; the booted bearing measures 1-1/2" OD x just shy of 11/16" ID x 1/2" thick, inside a 1-13/16" black rubber boot with a removable hex ID bushing.

Interesting concentric sealed bearing, like a pillow block, from Hub City. The outer portion measures 52mm dia x 15mm thick with an anti-rotation pin, and the inner measures  34mm dia x 12mm thick with a 22mm ID bore and (2) 3mm setscrews.

Biggest industrial bearing we’ve seen in a dog’s age, and we’ve got some old industrial dogs around here. This shielded, single-direction roller thrust bearing is 80mm OD x 30mm ID x 36mm thick. Unique bore. Will fit either 30mm square or 31mm round shaft. Part #208PP5.