I believe that those shadow bolster yellow knives came three ways that I can think of, although the 3 parameters might have been mixed (?). Anyway, number 1: Swinden pin construction with fake rivets that are not actually blade pivots; number 2: real blade pivot rivets (earlier, obviously), and number 3; whether they were yellow celluloid or yellow Delrin. The yellow celluloid found in this pattern was notoriously infamous for catastrophic failure. The knife posted above is Delrin and appears to have Swinden pin construction. I am basing this on something I read long ago and am not personally sure of what I am saying.