A fitting in the form of the letter y with each branch usually fixed at 45 degrees (0.78539 radians) to the run. It has identical flanged ends.
NSN 5910-01-550-9709
NSN 4140-01-158-6976
NSN 5905-00-946-6562
NSN 6105-00-147-2819
NSN 5945-01-080-3398
NSN 6130-01-469-1409
NSN 2925-00-656-3224
NSN 4140-00-226-4987
NSN 6135-01-601-6358
NSN 6685-01-360-9497
NSN 5990-01-356-4259
NSN 6650-00-361-1808