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 5930-00-775-6793
NSN 6135-01-434-1790
NSN 6240-01-176-9037
NSN 5835-00-861-6066
NSN 5930-00-109-8153
NSN 6650-01-100-0933
NSN 5905-01-617-9343
NSN 5855-01-568-4047
NSN 7035-01-091-7481
NSN 5950-01-439-7862
NSN 7035-00-179-3924
NSN 5990-01-154-7296