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 5835-00-670-2925
NSN 5905-00-168-9319
NSN 6130-01-458-7400
NSN 7035-00-215-3272
NSN 5920-01-174-8540
NSN 5925-01-620-4793
NSN 4140-00-980-7251
NSN 6150-01-613-4183
NSN 6685-01-634-0611
NSN 6240-01-064-0199
NSN 5910-01-525-0323
NSN 5960-01-564-5044