Indexing plungers are used to prevent any change in locking position due to lateral forces. A new locking position can only be set after the pin has been manually disengaged.
Form M is recommended for applications where the indexing plungers should remain disengaged over an extended period and the pin prevented from springing back.

If the indexing plunger is welded on, the sleeve should be tack welded so that the spring is not thermally damaged due to high temperatures.

Special versions.

Form L: non-lockout type
Form M: lockout type