An item with an integral porous or perforated plate, or with slits on the inside of a double wall.
NSN 5999-00-160-9701
NSN 5999-01-312-3064
NSN 6135-01-255-9129
NSN 6220-01-611-7723
NSN 5910-01-592-2746
NSN 5925-01-555-9563
NSN 5905-00-120-1315
NSN 6650-00-026-8139
NSN 2925-01-633-4048
NSN 6320-01-425-1417
NSN 5960-01-018-4162
NSN 5910-01-568-4483