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 6145-00-499-1131
NSN 6685-00-829-2797
NSN 6110-01-608-8058
NSN 5950-00-189-8004
NSN 5975-00-106-6145
NSN 6240-01-449-0746
NSN 2925-01-562-8051
NSN 7035-01-612-4535
NSN 6685-01-449-5833
NSN 6150-01-445-7253
NSN 4140-01-407-6595
NSN 7035-00-997-6212