Material is brass (copper alloy is the same thing), but the field is having problems with material definition.
A one-piece metal item, usually tubular, flanged at one end, the other end open. It is used primarily for lining and reinforcing the edges of holes. The unflanged end is designed to be inserted through a hole and crimped to form a mating flange. Excludes grommet, metallic and eyelets which are components of pushbutton, turnbutton and turnlock type fastners.
Classification: Hooks, eyes and eyelets, of base metal
NSN 5975-01-380-1908
NSN 6105-00-632-6564
NSN 6145-00-883-2090
NSN 5910-01-572-9036
NSN 5999-01-222-0389
NSN 5935-00-726-2419
NSN 6650-01-219-3731
NSN 6110-01-441-7370
NSN 5930-00-246-1319
NSN 5998-00-138-3717
NSN 5920-01-442-6756
NSN 6650-00-348-2453