An item with an integral porous or perforated plate, or with slits on the inside of a double wall.
NSN 6645-01-400-2119
NSN 5835-01-125-6676
NSN 6220-00-452-5308
NSN 5920-01-384-9776
NSN 5895-01-249-6701
NSN 5930-01-467-9523
NSN 5950-01-273-7987
NSN 6145-00-602-1413
NSN 6105-01-253-9517
NSN 6620-01-415-5803
NSN 6320-01-610-4410
NSN 6650-00-960-5040