Side flapper to indicate flow in one direction; not for vertical down flows
NSN 4140-01-413-3924
NSN 5905-01-516-6775
NSN 5999-01-459-9938
NSN 5915-00-492-1474
NSN 5895-01-024-9573
NSN 5855-01-410-8979
NSN 6135-01-556-7318
NSN 5915-01-420-5777
NSN 6620-01-262-9489
NSN 5985-01-430-3497
NSN 6620-01-451-0066
NSN 5975-01-048-9301