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 6650-01-207-0829
NSN 6145-01-493-1892
NSN 6105-01-307-9872
NSN 7035-01-412-3692
NSN 5945-01-221-7885
NSN 5925-01-260-1821
NSN 5855-00-198-3197
NSN 6220-00-707-5044
NSN 6610-00-496-7842
NSN 4140-00-669-6109
NSN 6145-01-350-9918
NSN 5855-00-494-9581