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 6645-00-583-0066
NSN 6685-01-076-4703
NSN 6685-00-933-4122
NSN 4140-01-305-2112
NSN 6610-01-604-7335
NSN 5905-00-772-2863
NSN 6135-01-394-4160
NSN 5960-00-195-4448
NSN 5945-00-800-1616
NSN 6240-01-502-6405
NSN 2925-01-342-1712
NSN 5920-00-636-3231