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 5930-01-441-3419
NSN 6240-00-266-9940
NSN 6685-01-058-4437
NSN 5930-01-129-9925
NSN 5895-01-644-5843
NSN 5930-01-281-3594
NSN 5935-01-555-1526
NSN 6135-00-299-6374
NSN 5920-01-085-8374
NSN 6320-01-264-2433
NSN 6610-01-119-7873
NSN 6620-01-205-3825