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 6320-01-592-4567
NSN 5935-01-104-4891
NSN 5920-01-426-8517
NSN 5960-00-972-9297
NSN 5895-00-175-6415
NSN 5930-01-053-5176
NSN 5910-01-317-4018
NSN 7035-01-455-7277
NSN 5965-01-437-9721
NSN 6320-00-695-3891
NSN 5905-00-615-9391
NSN 5965-01-059-4028