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 6150-00-871-9439
NSN 6110-01-184-9209
NSN 6110-01-106-5111
NSN 5920-01-381-9310
NSN 5950-00-866-1078
NSN 5960-00-722-6845
NSN 7035-01-565-6992
NSN
NSN 6320-00-456-2092
NSN 5950-00-816-9913
NSN 6320-01-240-4637
NSN 5999-01-241-5415