A washer or cone or disk shape with a centrally located hole, designed to accommodate a flat or oval head screw and provide additional bearing area on the material being fastened. It may or may not have a flush flange feature.
NSN 6110-01-013-9313
NSN 6110-01-111-8762
NSN 5910-00-901-6559
NSN 5905-00-766-4570
NSN 5990-01-067-1775
NSN 5950-00-155-4753
NSN 5990-00-625-2560
NSN 6220-01-555-8332
NSN 6105-01-527-9928
NSN 2925-01-633-4048
NSN 5950-01-357-3315
NSN 6105-00-088-7615