This standard fastener retaining ring pin circlip has even and moderate elastic force with proper clamping strength for tight fitting and anti-loosening effect after installation. Tough and wear-resistant, it adapts to high-speed operation and vibration environment inside gearboxes, not easy to lose elasticity due to aging. Easy to assemble and replace for maintenance, it stably fixes movable parts, suitable for ZF12AS series heavy-duty commercial gearboxes.