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 6620-00-889-7945
NSN 5996-00-692-6679
NSN 5935-00-901-0923
NSN 4140-01-553-7727
NSN 6220-01-023-8818
NSN 6240-01-089-6149
NSN 5990-01-546-1649
NSN 5915-00-373-7775
NSN 2925-01-244-3016
NSN 6240-00-097-8505
NSN 6240-01-515-2400
NSN 6220-01-124-1308