One quarter in an4 fitting with part number 2021-2-4s
NSN 4140-01-140-6781
NSN 5855-00-327-2112
NSN 6610-01-096-0894
NSN 5975-01-282-1897
NSN 6650-01-179-3823
NSN 5910-01-440-7916
NSN 5998-00-862-6396
NSN 6105-01-243-6998
NSN 5999-01-618-4136
NSN 5960-01-163-8905
NSN 6685-00-104-7149
NSN 5975-01-485-9246