One quarter in an4 fitting with part number 2021-2-4s
NSN 6105-00-120-9601
NSN 5990-01-480-9938
NSN 5965-01-646-6326
NSN 4140-01-096-0238
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NSN 5935-00-175-7621
NSN 6130-00-600-1971
NSN 6320-01-116-3980
NSN 5950-01-195-1388
NSN 5990-01-013-8464
NSN 5920-01-480-3697
NSN 5835-01-642-4705