The Fairchild C-119 Flying Boxcar fuselage windows had 16 rivet holes (see link)
http://www.schildhouse.com/aviation_files.html#fairchild_c119
Your photo clearly shows 20 holes. That said, both items were fabricated by Lockheed
PN: 337501
1560-00-304-2940
Retainer, Fuselage Window
CAGE: 98897 Lockheed
PN: 337501-3
Plenum, Compressor
(Appears to be the PN for plenum chamber valve) - that operates for pressure balancing via the ventilation tube and may also operate as acoustic silencer device.
2835-00-633-3403
CAGE: 98897 Lockheed