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 5960-01-021-6657
NSN 6320-00-468-8421
NSN 6320-01-116-3980
NSN 5920-01-463-4826
NSN 6105-00-466-9032
NSN 6130-00-008-5144
NSN 5975-01-443-1525
NSN 5935-00-519-0281
NSN 5990-01-411-5930
NSN 5895-00-961-2696
NSN 6645-01-400-2119
NSN 5910-00-335-8586