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 5945-00-930-3105
NSN 6645-01-189-0275
NSN 6240-01-043-5308
NSN 5915-01-082-1466
NSN 6105-01-029-3764
NSN 5985-01-623-3850
NSN 6145-00-604-6916
NSN 6110-00-754-7926
NSN 5998-01-357-7038
NSN 5925-00-408-8918
NSN 6685-01-530-0685
NSN 6130-01-349-2796