Company calls this a caster
A circular item made of metallic or nonmetallic material designed for use as part of a caster, rigid and/or caster, swivel. The tread may or may not be removeable and it is usually furnished with bearings installed. For items constructed entirely of one material see wheel(1), solid, metallic or wheel(1), solid, nonmetallic.
Classification: Hooks, eyes and eyelets, of base metal
NSN 4140-01-470-3577
NSN 5960-00-349-7650
NSN 5905-01-435-6227
NSN 5950-00-111-1366
NSN 6240-00-138-0654
NSN 5960-01-512-0233
NSN 6110-00-491-3801
NSN 5945-00-824-1577
NSN 6240-01-607-4746
NSN 5935-00-197-6703
NSN 6320-00-139-1090
NSN 6645-00-113-4441