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 5855-00-951-6483
NSN 6135-01-573-7164
NSN 5910-00-840-9870
NSN 5996-01-570-4583
NSN 5925-00-111-1748
NSN 4140-01-595-0741
NSN 5915-00-511-8241
NSN 6145-01-391-9705
NSN 6220-01-209-0030
NSN 6320-01-255-2096
NSN 5960-00-258-9292
NSN 5895-01-227-2651