An item with an integral porous or perforated plate, or with slits on the inside of a double wall.
NSN 5950-01-658-0032
NSN 5998-01-611-1974
NSN 5905-01-634-0595
NSN 5965-01-084-2385
NSN 5965-00-064-5435
NSN 4140-00-009-0233
NSN 7035-01-026-0117
NSN 6240-00-765-8443
NSN 4140-00-274-9638
NSN 5950-00-280-7825
NSN 5996-00-659-9187
NSN 6240-01-591-5107