1/4-19 thread size; 20.6 m o.D.; 13.7 mm i.D.; 2.0 mm width; used on k4 style straight fittings as a port seal
NSN 5965-01-408-9551
NSN 6145-01-460-6510
NSN 6610-01-181-4398
NSN 6320-00-676-9387
NSN 6240-01-361-8797
NSN 5985-00-740-7154
NSN 5915-01-212-8761
NSN 6110-01-212-5909
NSN 2925-00-898-9135
NSN 6320-01-418-6681
NSN 5998-01-505-1554
NSN 5915-01-385-6774