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 5945-00-070-1890
NSN 5895-00-859-5251
NSN 7035-00-834-2090
NSN 5920-01-278-0600
NSN 5835-01-589-4735
NSN 5999-00-817-7864
NSN 6110-01-415-3343
NSN 6145-00-643-4962
NSN 5910-00-190-1320
NSN 6150-01-529-9121
NSN 6145-01-041-1907
NSN 6610-01-339-6803