Cleaning and packaging per mil-std-1330d
A circular shaped item with an aperture manufactured to predetermined dimensions and designed for use as a seal in stuffing boxes, packing nuts, and the like. It may be (1) any nonmetallic molded or formed ring (except solid (without joint) rings having a square or rectangular cross section); or (2) any shredded metal or metal foil type metallic or semimetallic rings. Excludes felt items but includes multimaterial items in which one of the materials is felt. For solid (without joints) nonmetallic items with a square or rectangular cross section, see washer (as modified) and gasket. For rubber items specifically designed for weather-proofing doors, windows, chests, and the like see seal, nonmetallic angle; seal, nonmetallic channel; and seal, nonmetallic, special shaped section. For circular (with aperature) nonmetallic items with a solid round cross-section see o-ring. Excludes cup, compression; gasket; washer (as modified); and felt, mechanical, preformed.
Dept. of the Navy 
Brazil Classification: Gaskets,washers & other seals
NSN 5930-01-032-0001
NSN 6320-00-546-9249
NSN 6105-01-634-0322
NSN 5990-00-320-2779
NSN 6620-01-618-2962
NSN 5950-01-296-7567
NSN 5895-00-917-5733
NSN 4140-01-483-1993
NSN 5895-01-178-4061
NSN 6135-01-385-7276
NSN 5975-01-463-0376
NSN 5996-01-268-5206