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 6650-01-514-7809
NSN 6135-01-386-5709
NSN 5855-00-610-4052
NSN 6110-00-400-0778
NSN 6110-00-223-8684
NSN 5905-01-501-6048
NSN 6320-01-484-7734
NSN 5998-01-158-7974
NSN 5925-00-197-4329
NSN 5998-00-264-3088
NSN 6620-00-863-4639
NSN 6650-00-137-3845