The retaining ring for boring, 108×4, code 06.29020-0215.0, is a precision-engineered fastening element that ensures the secure axial positioning of components within the MAN L21/31 engine assembly. Manufactured from high-strength spring steel and machined to exact dimensional tolerances, it provides reliable locking performance even under continuous vibration, thermal expansion, and dynamic load conditions. Its function is essential for maintaining the integrity of rotating and reciprocating assemblies, preventing unwanted movement and ensuring accurate alignment during long operating cycles. By combining durability with ease of installation and removal, this retaining ring supports efficient maintenance procedures and contributes to the long-term operational reliability of marine and power-generation engines.