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 5910-01-083-7188
NSN 6610-00-235-9784
NSN 5945-01-030-2229
NSN 6610-01-119-7873
NSN 5998-00-189-0761
NSN 6105-01-438-2114
NSN 6220-00-922-3714
NSN 6320-01-306-8117
NSN 5855-01-443-3970
NSN 6150-01-041-8377
NSN 5965-01-024-7960
NSN 2925-01-420-2362