An item with an integral porous or perforated plate, or with slits on the inside of a double wall.
NSN 5945-01-554-6378
NSN 6620-01-392-6180
NSN 6220-01-535-3818
NSN 5998-01-424-8220
NSN 2925-00-707-6770
NSN 5925-00-001-5977
NSN 5835-00-233-6327
NSN 6650-01-154-1870
NSN 5910-01-044-5886
NSN 7035-01-602-7966
NSN 6685-00-226-1885
NSN 6220-01-597-2599