Self-locking nut

Listed on the following equipment:
Technogym - 700 JOG NOW (DAK31L)
Technogym - DAK3AV - DAK31V - 0.2
Technogym - Spin Trainer (D250U)
Technogym - Top 700 - D4773L - 2.0 (S/N D4773L08000161-Below)
Technogym - Top 700 - D4773L - 2.0 (S/N D4773L08000162-D4773L08000362)
Technogym - TOP Upper Body Trainer - DA7 (DA773W)

* Images may not be identical to part.