The lock ring works essentially as a strong low-compliance spring; when locked on a rod, the metal far from the rod is in compression while the metal just adjacent to the rod is in tension.
As a special high-temperature, spring-grade stainless steel is used to make the lock rings (not stainless steel type 304), the rings are mildly magnetic. This residual magnetism is normally too low to cause any difficulties except when working with electrons at very low energies.
The lock rings have the advantages of being easy to apply with a lock ring tool, of providing a very strong clamping action, and of requiring a minimal amount of axial space along the rod.
See Drawing above.