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 6150-01-542-6162
NSN 5920-00-021-3697
NSN 5945-01-202-8363
NSN 5975-01-160-6435
NSN 6220-01-172-3620
NSN 6105-01-027-1135
NSN 5965-00-351-7460
NSN 6150-01-032-4556
NSN 6610-01-250-9327
NSN 5999-01-296-0176
NSN 5855-00-408-2611
NSN 6645-00-406-2564