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 5999-00-983-9348
NSN 5930-01-613-5641
NSN 5965-01-633-4899
NSN 5915-01-042-2521
NSN 5965-01-237-3342
NSN 5905-01-200-5731
NSN 6620-01-362-5432
NSN 6610-01-284-6968
NSN 5975-01-411-6597
NSN 6610-01-507-4356
NSN 5960-01-512-0233
NSN 2925-01-265-2853