It’s a variable length thermoplastic roller lever that’s used in the obsolete XCKP XCKT plastic limit switches with black casing. The ZCKY46 is the same roller lever, just with a steel roller.

In the current range of XCKP XCKT blue limit switches with a plastic case, the equivalent lever for this the ZCY45. The ZCY45 lever is positive for safety applications, not ZCKY45.