This replacement part is displayed as number 290 on KM4 series KM4A1/KM4CQB/KM16BR diagrams and functions as the tightening mechanism for the carry handle lock.
This replacement part is displayed as number 76, 97 on LM4 PTR/KR Series diagram This replacement part is displayed as number 97 on /AKG74M/74SU/KCR diagram