First collar consists of thread size 3/8in dia, 16 unc-2a thd, 1.875 length
An externally threaded fastener whose threaded portion is of one nominal diameter, and whose unthreaded portion has been machined or ground in one or more places or over its entire length to a maximum diameter less than the minimum pitch diameter of the thread (excludes undercuts for thread relief). It is no. 10 (0.190 in.) (5 mm) or larger in size and has a head which is not designed to be held or driven with an inserted driver or designed for rotation by the thumb and fingers. A locking feature may be incorporated in the design of the head or threads. Excludes bolt, internal wrenching and thumbscrew. See also screw, externally relieved body.
Classification: Other copper screws (not for wood) bolts and nuts
NSN 5965-00-475-2759
NSN 4140-01-565-9408
NSN 6685-00-578-5951
NSN 5905-01-590-6927
NSN 6135-00-577-8429
NSN 2925-01-517-8544
NSN 5920-01-514-7007
NSN 6240-01-232-9496
NSN 5998-01-430-0454
NSN 4140-01-534-8592
NSN 5905-01-491-7600
NSN 5910-00-813-4057