An item with an integral porous or perforated plate, or with slits on the inside of a double wall.
NSN 5990-00-155-2306
NSN 5855-01-371-4998
NSN 7035-01-563-1646
NSN 5999-01-634-0576
NSN 5999-01-205-7533
NSN 7035-01-232-7263
NSN 5996-00-017-9189
NSN 5925-01-416-5603
NSN 6620-00-149-7557
NSN 5930-01-145-8741
NSN 6110-01-243-0446
NSN 6610-00-735-9555