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 5835-01-485-0210
NSN 5950-01-044-5039
NSN 5950-01-568-5324
NSN 5960-01-489-1510
NSN 5945-00-488-4815
NSN 6150-01-025-6305
NSN 6135-01-280-2883
NSN 6650-00-409-8949
NSN 7035-00-521-6423
NSN 6135-01-213-7339
NSN 5996-01-610-7449
NSN 6240-01-215-3512