There are two aperture on this item
A metallic or nonmetallic item which is rigid, flat and generally smooth. Its thickness is small in comparison to its length and width. It is designed for mounting another item and may have drilled or threaded holes or other facilities for mounting to a supporting object or surface. See support, as modified. Do not use if a more specific name applies.
NSN 5998-01-150-3457
NSN 5996-01-110-7706
NSN 5920-01-494-3470
NSN 5975-00-794-9413
NSN 6130-00-557-0607
NSN 4140-00-612-9727
NSN 5905-01-192-3112
NSN 6685-01-413-6487
NSN 5998-01-554-7714
NSN 6110-01-055-6442
NSN 5935-01-225-2678
NSN 6645-01-585-0018