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 6145-01-384-8819
NSN 6620-01-323-7620
NSN 6220-01-634-0660
NSN 5950-00-167-7650
NSN 5915-01-244-6772
NSN 5990-00-757-5262
NSN 6620-01-552-4980
NSN 5920-01-629-6934
NSN 6620-01-203-4369
NSN 6240-01-242-9138
NSN 5945-00-144-8073
NSN 5999-00-919-3991