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 6620-01-520-4186
NSN 4140-01-231-8578
NSN 5920-01-068-8574
NSN 6220-00-272-7497
NSN 5996-01-170-1915
NSN 5910-01-323-7086
NSN 5999-01-447-3153
NSN 5895-00-081-3293
NSN 5915-01-138-1382
NSN 5965-01-641-0237
NSN 5910-01-237-9380
NSN 5945-01-364-6919